Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries

*Satarupa Ghosh, Snigdha Chatterjee, Ghora Shiva Prasad and Prasanna Pal*

#### **Abstract**

The exploitation of nature for decades due to several anthropogenic activities has changed the climatic conditions worldwide. The environment has been polluted with an increase of greenhouse gases. The major consequences are global warming, cyclone, an increase in sea level, etc. It has a clear negative impact on the natural environment including aquatic ones. As a result, production of fish in the aquaculture system and marine system is greatly affected. Marine ecosystems like coral reefs are also destroyed. Decreased fish production has also affected the livelihood and economic condition of the fish farmers. So, corrective measures should be taken to reduce the climate changes for minimizing its effects on fish production. Using more eco-friendly substances, planting more trees, and preserving our nature are some steps to be taken. Awareness should also be generated among the common people.

**Keywords:** aquatic environment, economy, climate change, fish production, global warming

#### **1. Introduction**

For the last few decades, climate change, food security and their complex interaction have become a global issue [1]. With the rapid increase in human population, we have destroyed our nature and polluted the environment. The level of greenhouse gases in the atmosphere is increasing day by day. Consequently, we are facing the threats of global warming and other climatic changes like cyclone, drought, flood, etc. Change in the climatic conditions may be limited to a specific region or may occur across the whole earth. But, it is affecting all the ecosystems including the aquatic ones. Aquatic organisms are very vulnerable to climate change because the average temperature of both air and water are changing simultaneously. Climate change in the aquatic system mainly occurs through sea level and temperature rise, change in monsoon patterns, extreme weather events and water stress having both direct and indirect impacts on aquatic animals including fish stocks. It directly acts upon the physiological behavior and growth pattern of organisms, subsequently decrease reproductive capacity and finally cause mortality. Indirectly it may alter the productivity, structure, function and composition of aquatic ecosystems. All these effects finally result in decreased fish production. It disturbs the economic

condition of fish farmers and hamper their normal livelihood by huge economic losses. In this chapter, we will discuss how climate change affects the production of fish and the lives of fish farmers and how it could be mitigated through proper actions.

### **2. Causes of climate change**

The factors that can cause a change in the atmospheric system or climatic regime are called "climate forcing" or "forcing mechanisms." So, forcing mechanisms can be of two types, i.e., internal forcing mechanism and external forcing mechanisms. Internal forcing mechanisms are natural processes in the climatic system like thermohaline circulation, etc. External forcing mechanisms can also be of two types- anthropogenic mechanisms including greenhouse gas emission and the emission of several other pollutants and natural mechanisms like changes in solar output, volcanic eruptions, etc. All these mechanisms are responsible for the change of climate. But overwhelming evidence exists that anthropogenic activities are the major reason behind this dreadful condition. These are described below.


#### **3. Changes on aquatic ecosystem due to climate change**

#### **3.1 Temperature**

All the aquatic organisms including fish and aquatic invertebrates are poikilothermic in nature and the body temperature of those organisms changes with environmental temperature. So, they are very much sensitive to the change in the temperature in their external environment where they live. When the external environmental temperature goes beyond the tolerance limit of these organisms, they will go for migration to the place where their internal system allows them to regain their internal homeostasis. This procedure is termed as behavioral

**45**

*Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries*

thermoregulation [2]. This will result in rapid migration to the cooler zones of the water body [3]. This migration allows the shifting of the aquatic animals from shallow coastal waters and semi-enclosed areas into deeper cooler waters [4]. In spite of the negative impacts of these phenomenons like coral reef destruction and increased ocean acidification, it would have some conservative approach. This phenomenon of migration can alone reduce the maximum catch potential of the

As the major consequences of climate change, especially increased temperature strongly affects the recruitment process [5]. Some stocks may become intolerance to the sustainable fishing effort because they experience them as overfishing due to the side effects of temperature enhancement [6]. Temperature enhancement of water, where fish live, will slow down their growth and maximum size as the temperature

Local extinction of fish species would be noticed, among freshwater and diadromous species especially [7]. Because of the higher potential for migration, terrestrial species show a higher rate (15–37%) of overall migration than marine

The increased temperature would bring a deadly impact on reef fisheries by

The levels of light and temperature determine the availability of nutrients in the water body, which in turn affects the primary productivity. Due to climate variability, reduced precipitation would lead to reduced run-off from land, which caused the starvation of wetland and mangrove and damage local fisheries. In some other places, due to increased precipitation from extreme weather events like flooding, nutrient level in the water body tremendously increased causing eutrophication and washout fertilizer causing harmful algal blooms into the water bodies, known as red tides [2, 9]. Most of the small scale fisheries locate at the lower latitude, where climate change hit the most and decline the primary productivity [10] of the

**4. Impact of climate change on fish production and ecosystem**

wind-pattern will adversely affect the fisheries and aquaculture [3].

Fisheries and aquaculture are largely dependent on the interactions among the various factors like the earth's climate and ocean environment. So, changing the pattern of air and sea-surface temperatures, rainfall, sea level, ocean acidity and

Marine fish production is largely disrupted by climate change. With the change in the climatic conditions, several changes are observed in the ocean including a rise in temperature, melting of polar ice, rising sea level, change in ocean current system and acidification of seawater. Over the coming decades, the temperature of the Indian seas is going to increase by 1–3°C [11]. The species that is going to be affected first due to these conditions is plankton. It forms the basis of the food chain in the marine ecosystem. Other species including corals, fishes, sea birds will be affected simultaneously. Due to increased ocean acidification, marine organisms like oysters,

*DOI: http://dx.doi.org/10.5772/intechopen.93784*

would increase their metabolic rate [2].

inducing bleaching of the coral reef [7].

**3.2 Primary productivity**

tropics by 40% [4].

species [8].

fisheries sector.

**4.1 Aquaculture system**

*4.1.1 Marine system*

#### *Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries DOI: http://dx.doi.org/10.5772/intechopen.93784*

thermoregulation [2]. This will result in rapid migration to the cooler zones of the water body [3]. This migration allows the shifting of the aquatic animals from shallow coastal waters and semi-enclosed areas into deeper cooler waters [4]. In spite of the negative impacts of these phenomenons like coral reef destruction and increased ocean acidification, it would have some conservative approach. This phenomenon of migration can alone reduce the maximum catch potential of the tropics by 40% [4].

As the major consequences of climate change, especially increased temperature strongly affects the recruitment process [5]. Some stocks may become intolerance to the sustainable fishing effort because they experience them as overfishing due to the side effects of temperature enhancement [6]. Temperature enhancement of water, where fish live, will slow down their growth and maximum size as the temperature would increase their metabolic rate [2].

Local extinction of fish species would be noticed, among freshwater and diadromous species especially [7]. Because of the higher potential for migration, terrestrial species show a higher rate (15–37%) of overall migration than marine species [8].

The increased temperature would bring a deadly impact on reef fisheries by inducing bleaching of the coral reef [7].

#### **3.2 Primary productivity**

*Inland Waters - Dynamics and Ecology*

**2. Causes of climate change**

warming.

increasing.

**3.1 Temperature**

to global warming in broad sense.

actions.

condition of fish farmers and hamper their normal livelihood by huge economic losses. In this chapter, we will discuss how climate change affects the production of fish and the lives of fish farmers and how it could be mitigated through proper

The factors that can cause a change in the atmospheric system or climatic regime are called "climate forcing" or "forcing mechanisms." So, forcing mechanisms can be of two types, i.e., internal forcing mechanism and external forcing mechanisms. Internal forcing mechanisms are natural processes in the climatic system like thermohaline circulation, etc. External forcing mechanisms can also be of two types- anthropogenic mechanisms including greenhouse gas emission and the emission of several other pollutants and natural mechanisms like changes in solar output, volcanic eruptions, etc. All these mechanisms are responsible for the change of climate. But overwhelming evidence exists that anthropogenic activities are the

• Fossil fuel burning: Fossil fuel burning is one of the most important sources of climate change. As fossil fuels contain carbon for many years, they can release back CO2 into the air. This is one of the direct causes of carbon emission in the air, which can cause all sorts of environmental problems including global

• Livestock farming: Through livestock farming, methane (CH4) gas is emitted into the atmosphere. As we know, CH4 is a greenhouse gas, so capable of trapping a huge amount of heat from the sun. In that way, they can contribute

• Aerosols: Aerosols also represent a big problem for the climate today. Aerosols are a very small naturally occurring particle in the atmosphere. Previously the number of aerosols in the atmosphere was very less, but now the level is

• Use of fertilizers: Use of fertilizers in both agricultural and aquacultural farmland can increase the availability of food source greatly to us. To meet up the growing demand for food, the use of fertilizers have increased rapidly. Fertilizer contains a huge amount of nitrous oxide, which is responsible for a

All the aquatic organisms including fish and aquatic invertebrates are poikilothermic in nature and the body temperature of those organisms changes with environmental temperature. So, they are very much sensitive to the change in the temperature in their external environment where they live. When the external environmental temperature goes beyond the tolerance limit of these organisms, they will go for migration to the place where their internal system allows them to regain their internal homeostasis. This procedure is termed as behavioral

steady increase in the earth's surface temperature.

**3. Changes on aquatic ecosystem due to climate change**

major reason behind this dreadful condition. These are described below.

**44**

The levels of light and temperature determine the availability of nutrients in the water body, which in turn affects the primary productivity. Due to climate variability, reduced precipitation would lead to reduced run-off from land, which caused the starvation of wetland and mangrove and damage local fisheries. In some other places, due to increased precipitation from extreme weather events like flooding, nutrient level in the water body tremendously increased causing eutrophication and washout fertilizer causing harmful algal blooms into the water bodies, known as red tides [2, 9]. Most of the small scale fisheries locate at the lower latitude, where climate change hit the most and decline the primary productivity [10] of the fisheries sector.

#### **4. Impact of climate change on fish production and ecosystem**

#### **4.1 Aquaculture system**

Fisheries and aquaculture are largely dependent on the interactions among the various factors like the earth's climate and ocean environment. So, changing the pattern of air and sea-surface temperatures, rainfall, sea level, ocean acidity and wind-pattern will adversely affect the fisheries and aquaculture [3].

#### *4.1.1 Marine system*

Marine fish production is largely disrupted by climate change. With the change in the climatic conditions, several changes are observed in the ocean including a rise in temperature, melting of polar ice, rising sea level, change in ocean current system and acidification of seawater. Over the coming decades, the temperature of the Indian seas is going to increase by 1–3°C [11]. The species that is going to be affected first due to these conditions is plankton. It forms the basis of the food chain in the marine ecosystem. Other species including corals, fishes, sea birds will be affected simultaneously. Due to increased ocean acidification, marine organisms like oysters, shrimps and corals would unable to form their outer covering or shell through the process of calcification. Thus, the entire marine food web get affected because of the formation of cracks in the marine food chain.

#### *4.1.2 Freshwater systems*

The vulnerability of the freshwater ecosystems against climate change is very high. The size, depth and trophic status of the lake determine the vulnerability of this system against climate change. According to Field and coworkers [12], the negative impact was observed on the cold-water species and positive impact on the warm-water species. Due to acute effects of climate change, alteration of shapes and distribution is seen in the freshwater lake system and in some cases, they might be disappeared. These are the attributes of the dynamics change in precipitation, evaporation and run-off [13]. Climate change promotes long-term increases in fish-production by inducing the enhancement of the production rate of invertebrate prey logarithmically with increasing temperature. The increasing rates are 2–4 times for each 10°C increase in temperature [14]. But on the other hand, climate change will result in a change in prey-species composition. This change may cause antagonistic effects on the long-term enhancement of fish production [14]. In short-time, climate change will cause a decrease in fish-production because of timing mismatch [14]. The ability of the movement of the freshwater species is vital in determining the resistance of those species to withstand climate change [13].

#### **4.2 Coral reef**

The coral reef is an important source of income for many developing countries [15]. Coral provides habitat for more than half of all marine species. But now coral reefs of the ecosystem are in great danger. The main reasons are increasing temperature, acidity, etc.

Climate change-related impact on the coral reef can be based on three different time-scales.


The coral reef is one of the most resistant ecosystems and too resilient to recover from weak chronic as well as acute stresses [16]. But according to Hughes and coworkers [17], the reef ecosystem is not able to sustain against chronic plus acute stress.

Increasing acidity causes decreasing the pH of the ocean, which results in decreased aragonite saturation that can disrupt the calcification of coral [18]. Enhanced acidity of the world's ocean is very much important and represents a long-term threat to coral reefs but the impact growth of the corals on the increasing acidity is unknown [15]. The saturation level of aragonite in deep cold water corals are 90–150 m [19]. The impact of the acidification is badly seen in these deep- cold-water corals.

If corals are decreased due to adverse impacts from climatic change, it causes a negative impact on the reef fish- biodiversity [20]. According to Grandcourt and

**47**

**of climate change**

*Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries*

Cesar [21], coastal fisheries are badly affected by the warming of the climate and bleaching events. It can be concluded that coral reef destruction causes a long-term impact on the animals which depends on these reefs for their food and habitat.

Climate change acts as an important determinant of the distribution of biodiversity in past and future aspect [22–26]. Environmental factors reflect strong influences upon species richness of aquatic organisms [27]. Ocean warming can cause change to the marine species especially in their latitudinal range [28–30] and depth range [31]. At a larger scale, such changes can lead to local extinction and invasions and shifting to their bio-geographic pattern [28]. As a result, a huge shift in species richness can occur which is regarded as the main cause of disruption of marine biodiversity and ecosystem [2, 32, 33]. The climate in the aquatic environment can

affect biodiversity, community structure and ecosystem function [34–37].

Change in the aquatic environment has a direct impact on the lives of the fish farmers. Due to disturbed fish production, farmers face economic losses. Besides global warming, cyclone is another problem that affects the lives of the farmers. Cyclone combined with a flood and heavy rainfall creates a major problem every year for the farmers especially in the coastal states of India. It is a matter of great concern that the frequency of intense tropical cyclones has increased in the Indian ocean [38]. The factors such as warm sea temperature, high humidity and instability of atmosphere are responsible for intensifying the cyclone [39]. As a consequence of global warming, the temperature of the Indian Ocean has also increased promoting devastating cyclones. In May 2019, a cyclone named Fani hit Andhra Pradesh, Odisha and West Bengal. It caused damage to the coastal land, boats, jetties and the shelters of the fishermen and five lakh houses were destroyed in 14 districts [40]. In Odisha only, the losses were estimated to be 12,000 crores. Regarding the seafood sector, the production of shrimp was declined by 60–70% [41]. Most recently, in May 2020, cyclone Amphan hit eastern India specifically West Bengal and alos Bangladesh. This was the first super cyclone in Bay of Bengal since 1999 super cyclone that hit Odisha took the life of more than 9000 people [42]. Amphan affected the coastal areas of West Bengal including East Midnapur, North 24 Parganas, South 24 Parganas, Kolkata, Hoogly and Howrah. According to Chief Minister of West Bengal, the death toll was more than 86 and the state suffered a damage of 1 lakh crore rupees (15.38 Billion USD) [43]. Specially, the Sundarban areas were highly devastated, millions of homes were damaged breached embankments led to flood in villages. It takes years for the local residents as well as fishermen to recover from these situations. They do not have shelter to stay, do not have a boat for fishing and no money to pay back the loans that ultimately affects their

**5. Economical crisis of the fish farmers due to climate change**

psychological health sometimes leading to suicidal tendencies.

**6. Adaptation and mitigation measures to reduce the effects** 

Consideration of future climate changes in advance and making them a part of short-term decision making is known as adaptation. This includes using more eco-friendly substances, planting more trees and preserving our nature as much as

*DOI: http://dx.doi.org/10.5772/intechopen.93784*

**4.3 Global marine biodiversity**

Cesar [21], coastal fisheries are badly affected by the warming of the climate and bleaching events. It can be concluded that coral reef destruction causes a long-term impact on the animals which depends on these reefs for their food and habitat.

#### **4.3 Global marine biodiversity**

*Inland Waters - Dynamics and Ecology*

*4.1.2 Freshwater systems*

**4.2 Coral reef**

time-scales.

acute stress.

deep- cold-water corals.

temperature, acidity, etc.

tion of reefs.

large scale composition shifts.

the formation of cracks in the marine food chain.

shrimps and corals would unable to form their outer covering or shell through the process of calcification. Thus, the entire marine food web get affected because of

The vulnerability of the freshwater ecosystems against climate change is very high. The size, depth and trophic status of the lake determine the vulnerability of this system against climate change. According to Field and coworkers [12], the negative impact was observed on the cold-water species and positive impact on the warm-water species. Due to acute effects of climate change, alteration of shapes and distribution is seen in the freshwater lake system and in some cases, they might be disappeared. These are the attributes of the dynamics change in precipitation, evaporation and run-off [13]. Climate change promotes long-term increases in fish-production by inducing the enhancement of the production rate of invertebrate prey logarithmically with increasing temperature. The increasing rates are 2–4 times for each 10°C increase in temperature [14]. But on the other hand, climate change will result in a change in prey-species composition. This change may cause antagonistic effects on the long-term enhancement of fish production [14]. In short-time, climate change will cause a decrease in fish-production because of timing mismatch [14]. The ability of the movement of the freshwater species is vital in determining the resistance of those species to withstand climate change [13].

The coral reef is an important source of income for many developing countries

Climate change-related impact on the coral reef can be based on three different

• Years: Coral bleaching which increased in recent years and results in degrada-

• A few decades: Acidification increased and carbonate structures degenerate.

• Multi-decades: Weakened the structural integrity of the reefs which causes

The coral reef is one of the most resistant ecosystems and too resilient to recover from weak chronic as well as acute stresses [16]. But according to Hughes and coworkers [17], the reef ecosystem is not able to sustain against chronic plus

Increasing acidity causes decreasing the pH of the ocean, which results in decreased aragonite saturation that can disrupt the calcification of coral [18]. Enhanced acidity of the world's ocean is very much important and represents a long-term threat to coral reefs but the impact growth of the corals on the increasing acidity is unknown [15]. The saturation level of aragonite in deep cold water corals are 90–150 m [19]. The impact of the acidification is badly seen in these

If corals are decreased due to adverse impacts from climatic change, it causes a negative impact on the reef fish- biodiversity [20]. According to Grandcourt and

[15]. Coral provides habitat for more than half of all marine species. But now coral reefs of the ecosystem are in great danger. The main reasons are increasing

**46**

Climate change acts as an important determinant of the distribution of biodiversity in past and future aspect [22–26]. Environmental factors reflect strong influences upon species richness of aquatic organisms [27]. Ocean warming can cause change to the marine species especially in their latitudinal range [28–30] and depth range [31]. At a larger scale, such changes can lead to local extinction and invasions and shifting to their bio-geographic pattern [28]. As a result, a huge shift in species richness can occur which is regarded as the main cause of disruption of marine biodiversity and ecosystem [2, 32, 33]. The climate in the aquatic environment can affect biodiversity, community structure and ecosystem function [34–37].

### **5. Economical crisis of the fish farmers due to climate change**

Change in the aquatic environment has a direct impact on the lives of the fish farmers. Due to disturbed fish production, farmers face economic losses. Besides global warming, cyclone is another problem that affects the lives of the farmers. Cyclone combined with a flood and heavy rainfall creates a major problem every year for the farmers especially in the coastal states of India. It is a matter of great concern that the frequency of intense tropical cyclones has increased in the Indian ocean [38]. The factors such as warm sea temperature, high humidity and instability of atmosphere are responsible for intensifying the cyclone [39]. As a consequence of global warming, the temperature of the Indian Ocean has also increased promoting devastating cyclones. In May 2019, a cyclone named Fani hit Andhra Pradesh, Odisha and West Bengal. It caused damage to the coastal land, boats, jetties and the shelters of the fishermen and five lakh houses were destroyed in 14 districts [40]. In Odisha only, the losses were estimated to be 12,000 crores. Regarding the seafood sector, the production of shrimp was declined by 60–70% [41]. Most recently, in May 2020, cyclone Amphan hit eastern India specifically West Bengal and alos Bangladesh. This was the first super cyclone in Bay of Bengal since 1999 super cyclone that hit Odisha took the life of more than 9000 people [42]. Amphan affected the coastal areas of West Bengal including East Midnapur, North 24 Parganas, South 24 Parganas, Kolkata, Hoogly and Howrah. According to Chief Minister of West Bengal, the death toll was more than 86 and the state suffered a damage of 1 lakh crore rupees (15.38 Billion USD) [43]. Specially, the Sundarban areas were highly devastated, millions of homes were damaged breached embankments led to flood in villages. It takes years for the local residents as well as fishermen to recover from these situations. They do not have shelter to stay, do not have a boat for fishing and no money to pay back the loans that ultimately affects their psychological health sometimes leading to suicidal tendencies.

#### **6. Adaptation and mitigation measures to reduce the effects of climate change**

Consideration of future climate changes in advance and making them a part of short-term decision making is known as adaptation. This includes using more eco-friendly substances, planting more trees and preserving our nature as much as possible. On another hand, preventing the chances of climate change, before it has occurred, reducing the effects of climate change in case of occurrence is known as mitigation. Reducing the carbon footprint and related activities should be a major step. The level of environmental pollution should be decreased as soon as possible before it becomes too late to act. Some strategies that we should follow immediately are discussed below.

Adaptation of forest conservation measures: Forest plays an important role in maintaining equilibrium in our ecosystem. We should conserve and prevent the destruction of forest land through afforestation as well as reforestation and prohibit the use of forestland for nonforest purposes to meet the livelihood of local people.

Inclusion of climate-study in the school-level educational system: If we want to generate awareness in the young generation by the introduction of climate-related study along with traditional educational system with the help of governmental initiatives. This will help to grow the consciousness among the young generation from very beginning which will significantly broaden this culture at the local, state and national levels.

Slowing down of population growth: Population growth is becoming a burden especially in the case of a developing country like India. It has become a major obstruction in achieving social and economic development. So, in order to fight against climate change, population pressure over the area need to be reduced by reversing down the population growth curve in developing countries.

Integration of climate issue with economic planning: Climate protection-related policies and programs should be incorporated into the local, state and national levels in order to encourage the integration of climate issues with economic planning and management.

#### **7. Recommendation for better management of fisheries against climate changes**


#### **8. Steps for sustaining the fish production and economy against climate change**

There is a crucial knowledge gap between fisheries, aquaculture management and climate change that need to be filled practically. In order to assess the risk of

**49**

**10. Conclusion**

coming threats.

*Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries*

climate change to coastal communities, human and institutional capacity building should be strengthened and proper adaptation and mitigation measures should be implemented. Therefore, well managed fisheries and aquaculture could give birth to a healthy and productive ecosystem. Careful use of coastal areas and catchment areas should be cross-sectoral responsibility to encourage the building process of a healthy and productive ecosystem. Moreover, youth engagement in each and every policy and decision-making process related to aquaculture and fisheries both at continental and national levels should be institutionalized efficiently as youth are

**9. Positive effects of climate change on the aquatic environment**

winter temperature –falling has decreased.

cost of fuel has also become cut down.

• **Slowed down the winter death rate of aquatic organisms:** Water temperature is one of the most crucial factors in determining the survival of aquatic animals. Many years ago, especially before the drastic climate change, winters were too cold to maintain the minimum metabolic rate of the aquatic organisms and the consequent death rate has increased rapidly. As a result of climate change, the average temperature of the water body increased so rapidly that winter has now become bearable considerably. So, the number of death due to

• **Reduction of the fuel cost of the aquatic environment:** As a result of climate change, heat energy becomes available and affordable at a cheaper rate. So, the demand for fuel in the aquatic environment has decreased and the consequent

• **Growth in aquaculture production:** Some thermophilic organisms living in the aquatic environment demand high temperature for maintaining their metabolic rate at an optimum level. The excess heat which is introduced as a result of climate change meets the demand of those aquatic organisms. So, in

Climate change is a major threat to both aquatic and terrestrial ecosystems. In present days, a random population explosion increases fossil fuel burning, industrialization, deforestation, and profit-oriented capitalism, which can, in turn, create synergistic effects on climate change. Aquaculture sector is much impacted by temperature increase in water and air, sea level rise, and associated water intrusion as affected by global warming and climate change. This change in the aquatic environment or a decrease in fish production is directly affecting the economic sustainability of fish farmers. Thus, this situation can be corrected if necessary actions will be taken in reducing environmental pollution as soon as possible. Researchers, economists, policymakers, and farmers should act together to fight economic instability and maintain harmony with nature. One thing we should remember that we should protect nature if we want to protect ourselves from the

that way, climate change benefited the overall aquacultural yield.

*DOI: http://dx.doi.org/10.5772/intechopen.93784*

the backbone of our society.

*Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries DOI: http://dx.doi.org/10.5772/intechopen.93784*

climate change to coastal communities, human and institutional capacity building should be strengthened and proper adaptation and mitigation measures should be implemented. Therefore, well managed fisheries and aquaculture could give birth to a healthy and productive ecosystem. Careful use of coastal areas and catchment areas should be cross-sectoral responsibility to encourage the building process of a healthy and productive ecosystem. Moreover, youth engagement in each and every policy and decision-making process related to aquaculture and fisheries both at continental and national levels should be institutionalized efficiently as youth are the backbone of our society.

#### **9. Positive effects of climate change on the aquatic environment**


#### **10. Conclusion**

*Inland Waters - Dynamics and Ecology*

are discussed below.

and national levels.

planning and management.

**climate changes**

and aquaculture.

**climate change**

possible. On another hand, preventing the chances of climate change, before it has occurred, reducing the effects of climate change in case of occurrence is known as mitigation. Reducing the carbon footprint and related activities should be a major step. The level of environmental pollution should be decreased as soon as possible before it becomes too late to act. Some strategies that we should follow immediately

Adaptation of forest conservation measures: Forest plays an important role in maintaining equilibrium in our ecosystem. We should conserve and prevent the destruction of forest land through afforestation as well as reforestation and prohibit the use of forestland for nonforest purposes to meet the livelihood of local people. Inclusion of climate-study in the school-level educational system: If we want to generate awareness in the young generation by the introduction of climate-related study along with traditional educational system with the help of governmental initiatives. This will help to grow the consciousness among the young generation from very beginning which will significantly broaden this culture at the local, state

Slowing down of population growth: Population growth is becoming a burden especially in the case of a developing country like India. It has become a major obstruction in achieving social and economic development. So, in order to fight against climate change, population pressure over the area need to be reduced by

Integration of climate issue with economic planning: Climate protection-related

• The ecosystem approach should be comprehensive, sound, integrated, compact and revised to make complete management of sand oceans of coasts, fisheries

• Environmental friendly aquaculture and fishing practices to be undertaken.

• Over-fishing and excess fishing capacity should be eliminated through the

policies and programs should be incorporated into the local, state and national levels in order to encourage the integration of climate issues with economic

reversing down the population growth curve in developing countries.

**7. Recommendation for better management of fisheries against** 

• Fuel-efficient aquaculture and fishing practices to be undertaken.

• Risk assessments should be proper and accurate at the local level.

**8. Steps for sustaining the fish production and economy against** 

• Exploration of the carbon sequestration process by aquatic ecosystems.

There is a crucial knowledge gap between fisheries, aquaculture management and climate change that need to be filled practically. In order to assess the risk of

• Integration of climate-proof aquaculture with other sectors.

implementation of reduced subsidy systems.

**48**

Climate change is a major threat to both aquatic and terrestrial ecosystems. In present days, a random population explosion increases fossil fuel burning, industrialization, deforestation, and profit-oriented capitalism, which can, in turn, create synergistic effects on climate change. Aquaculture sector is much impacted by temperature increase in water and air, sea level rise, and associated water intrusion as affected by global warming and climate change. This change in the aquatic environment or a decrease in fish production is directly affecting the economic sustainability of fish farmers. Thus, this situation can be corrected if necessary actions will be taken in reducing environmental pollution as soon as possible. Researchers, economists, policymakers, and farmers should act together to fight economic instability and maintain harmony with nature. One thing we should remember that we should protect nature if we want to protect ourselves from the coming threats.

*Inland Waters - Dynamics and Ecology*

### **Author details**

Satarupa Ghosh1 \*, Snigdha Chatterjee2 , Ghora Shiva Prasad1 and Prasanna Pal3

1 Department of Aquatic Environment Management, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India

2 Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India

3 Animal Physiology Division, ICAR-National Dairy Research Institute, Karnal, Haryana, India

\*Address all correspondence to: satarupasonaibfsc07@gmail.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**51**

*Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries*

[10] FAO. Climate change implications for fisheries and aquaculture. In: The State of Fisheries and Aquaculture 2008. Rome, Italy: FAO; 2008. pp. 87-91

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[13] Poff NL, Brinson MM, Day JWJ. Aquatic ecosystems and Global climate change: Potential Impacts on Inland Freshwater and Coastal Wetland Ecosystems in the United States. 2002. Available from: www.pewclimate.org

[Retrieved: 26 June 2019]

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[15] Parry M, Parry ML, Canziani O, Palutikof J, Van der Linden P, Hanson C.

Climate Change 2007—Impacts, Adaptation and Vulnerability: Working Group II Contribution to the Fourth Assessment Report of the IPCC. Cambridge: Cambridge University

[16] Buddemeier RW, Kleypas JA, Aronson RB. Potential Contributions of Climate Change to Stresses on Coral Reef Ecosystems. Coral Reefs and Global Climate Change. Virginia, USA:

[11] Ralbam V. Impact of climate change on Indian marine fisheries and option for adaptation. In: Lobster Research in India. Kochi, India: CMFRI; 2010. pp. 65-71. DOI: 10.1097/

NRL.0000000000000102

pp. 617-652

2001

Press; 2007

*DOI: http://dx.doi.org/10.5772/intechopen.93784*

2019;**363**(6430):930-931. DOI: 10.1126/

[2] Roessig JM, Woodley CM, Cech JJ, Hansen LJ. Effects of global climate change on marine and estuarine fishes and fisheries. Reviews in Fish Biology and Fisheries. 2004;**14**(2):251-275

[3] Cochrane K, Young C. De, Bahri, T. Climate change implications for

fisheries and aquaculture. FAO Fisheries and Aquaculture Technical Paper.

[4] Cheung WW, Lam VW, Sarmiento JL, Kearney K, Watson REG, Zeller D, et al. Large-scale redistribution of maximum fisheries catch potential in the global ocean under climate change. Global Change Biology. 2010;**16**(1):24-35

[5] Walther GR, Post E, Convey P, Menzel A, Parmesan C, Beebee TJ, et al. Ecological responses to recent climate change. Nature. 2002;**416**(6879):389

[6] Easterling WE, Aggarwal PK, Batima P, Brander KM, Erda L,

[7] IPCC. Climate change 2007: Synthesis report. In: Pauchauri RK, Reisinger A, editors. Contribution of Working Groups I, II, and III to the Fourth Intergovernmental Panel on Climate Change. Core Writing Team. Geneva, Switzerland: IPCC; 2007. p. 8

Howden SM, et al. Food, fibre and forest products. Climate Change. 2007:273-313

[8] Cheung WW, Lam VW, Sarmiento JL, Kearney K, Watson R, Pauly D. Projecting global marine biodiversity impacts under climate change scenarios. Fish and Fisheries. 2009;**10**(3):235-251

[9] Epstein PR. Is global warming harmful to health? Scientific American.

2000;**283**(2):50-57

[1] Plagányi É. Climate change impacts on fisheries. Science.

**References**

science.aaw5824

2009;**530**:212

*Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries DOI: http://dx.doi.org/10.5772/intechopen.93784*

#### **References**

*Inland Waters - Dynamics and Ecology*

**50**

**Author details**

Satarupa Ghosh1

Karnal, Haryana, India

\*, Snigdha Chatterjee2

Animal and Fishery Sciences, Kolkata, West Bengal, India

Viswavidyalaya, Mohanpur, Nadia, West Bengal, India

provided the original work is properly cited.

, Ghora Shiva Prasad1

1 Department of Aquatic Environment Management, West Bengal University of

2 Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

3 Animal Physiology Division, ICAR-National Dairy Research Institute,

\*Address all correspondence to: satarupasonaibfsc07@gmail.com

and Prasanna Pal3

[1] Plagányi É. Climate change impacts on fisheries. Science. 2019;**363**(6430):930-931. DOI: 10.1126/ science.aaw5824

[2] Roessig JM, Woodley CM, Cech JJ, Hansen LJ. Effects of global climate change on marine and estuarine fishes and fisheries. Reviews in Fish Biology and Fisheries. 2004;**14**(2):251-275

[3] Cochrane K, Young C. De, Bahri, T. Climate change implications for fisheries and aquaculture. FAO Fisheries and Aquaculture Technical Paper. 2009;**530**:212

[4] Cheung WW, Lam VW, Sarmiento JL, Kearney K, Watson REG, Zeller D, et al. Large-scale redistribution of maximum fisheries catch potential in the global ocean under climate change. Global Change Biology. 2010;**16**(1):24-35

[5] Walther GR, Post E, Convey P, Menzel A, Parmesan C, Beebee TJ, et al. Ecological responses to recent climate change. Nature. 2002;**416**(6879):389

[6] Easterling WE, Aggarwal PK, Batima P, Brander KM, Erda L, Howden SM, et al. Food, fibre and forest products. Climate Change. 2007:273-313

[7] IPCC. Climate change 2007: Synthesis report. In: Pauchauri RK, Reisinger A, editors. Contribution of Working Groups I, II, and III to the Fourth Intergovernmental Panel on Climate Change. Core Writing Team. Geneva, Switzerland: IPCC; 2007. p. 8

[8] Cheung WW, Lam VW, Sarmiento JL, Kearney K, Watson R, Pauly D. Projecting global marine biodiversity impacts under climate change scenarios. Fish and Fisheries. 2009;**10**(3):235-251

[9] Epstein PR. Is global warming harmful to health? Scientific American. 2000;**283**(2):50-57

[10] FAO. Climate change implications for fisheries and aquaculture. In: The State of Fisheries and Aquaculture 2008. Rome, Italy: FAO; 2008. pp. 87-91

[11] Ralbam V. Impact of climate change on Indian marine fisheries and option for adaptation. In: Lobster Research in India. Kochi, India: CMFRI; 2010. pp. 65-71. DOI: 10.1097/ NRL.0000000000000102

[12] Field CB, Mortsch LD, Brklasich M, Forbes DL, Kovacs P, Patz JA, et al. North America. In: Parry ML, Canziani OF, Palutikof JP, Hanson PJ, Linden v d CE, editors. Climate Change 2007: Impacts, Adaptation and Vulnerability. Cambridge: Cambridge University Press; 2007. pp. 617-652

[13] Poff NL, Brinson MM, Day JWJ. Aquatic ecosystems and Global climate change: Potential Impacts on Inland Freshwater and Coastal Wetland Ecosystems in the United States. 2002. Available from: www.pewclimate.org [Retrieved: 26 June 2019]

[14] Watson RT, Zinyowera MC, Moss RH, Dokken DJ. IPCC Special Report: The Regional Impacts of Climate Change: An Assessment of Vulnerability. United Nations: IPCC; 2001

[15] Parry M, Parry ML, Canziani O, Palutikof J, Van der Linden P, Hanson C. Climate Change 2007—Impacts, Adaptation and Vulnerability: Working Group II Contribution to the Fourth Assessment Report of the IPCC. Cambridge: Cambridge University Press; 2007

[16] Buddemeier RW, Kleypas JA, Aronson RB. Potential Contributions of Climate Change to Stresses on Coral Reef Ecosystems. Coral Reefs and Global Climate Change. Virginia, USA: Pew Center on Global Climate Change; 2004

[17] Hughes TP, Baird AH, Bellwood DR, Card M, Connolly SR, Folke C, et al. Climate change, human impacts, and the resilience of coral reefs. Science. 2003;**301**(5635):929-933. DOI: 10.1126/ science.1085046

[18] Orr JC, Fabry VJ, Aumont O, Bopp L, Doney SC, Feely RA, et al. Anthropogenic Ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature. 2005;**437**(7059):681-686. DOI: 10.1038/ nature04095

[19] Feely RA, Fabry VJ, Guinotte JM. Ocean Acidification of the North Pacific Ocean. Vol. 2. PICES press; 2007. Retrieved from: http://www.pices.int/ publications/pices\_press/volume16/ v16\_n1/pp\_22-26\_Acidification\_f.pdf

[20] Jones GP, McCormick MI, Srinivasan M, Eagle JV. Coral decline threatens fish biodiversity in marine reserves. Proceedings of the National Academy of Sciences. 2004;**101**:8251-8253

[21] Grandcourt EM, Cesar HS. The bio-economic impact of mass coral mortality on the coastal reef fisheries of the Seychelles. Fisheries Research. 2003;**60**(2):539-550

[22] Parmesan C, Yohe G. A globally coherent fingerprint of climate change impacts across natural systems. Nature. 2003;**421**:37-42. Crossref | CAS | PubMed |

[23] Peterson AT, Ortega-Huerta MA, Bartley J, Sánchez-Cordero V, Soberón J, Buddemeier RH, et al. Future projections for Mexican faunas under global climate change scenarios. Nature. 2002;**416**:626-629

[24] Root TL, Price JT, Hall KR, Schneider SH, Roxenzweiq C,

Pounds JA. Fingerprints of global warming on wild animals and plants. Nature. 2003;**421**:57-60

[25] Rosenzweig C, Karoly D, Vicarelli M, et al. Attributing physical and biological impacts to anthropogenic climate change. Nature. 2008;**453**:353-357

[26] Thomas CD, Williams SE, Cameron A, et al. Biodiversity conservation: Uncertainty in predictions of extinction risk/effects of changes in climate and land use/climate change and extinction risk. Nature. 2004;**430**:1-2

[27] Macpherson E. Large-scale speciesrichness gradients in the Atlantic Ocean. Proceedings of the Royal Society of London Series B. 2002;**269**:1715-1720

[28] Hiddink JG, Hofstede RT. Climate induced increases in species richness of marine shes. Global Change Biology. 2008;**14**:453-460

[29] Mueter FJ, Litzow MA. Sea ice retreat alters the biogeography of the Bering Sea continental shelf. Ecological Applications. 2008;**18**(2):309-320

[30] Perry AL, Low PJ, Ellis JR, Reynolds JD. Climate change and distribution shifts in marine shes. Science. 2005;**308**:1912-1915

[31] Dulvy NK, Rogers SI, Jennings S, Vanessa S, Dye SR, Skjoldal HR. Climate change and deepening of the North Sea sh assemblage: A biotic indicator of warming seas. Journal of Applied Ecology. 2008;**45**:1029-1039

[32] Cheung WWL, Lam VWY, Pauly D. Modelling Present and Climate-Shifted Distribution of Marine Fishes and Invertebrates. Fisheries Centre Research Report 16(3). Vancouver: University of British Columbia; 2008

[33] Worm B, Barbier EB, Beaumont N, et al. Impacts of biodiversity loss on ocean ecosystem services. Science. 2006;**314**:787-790

**53**

*Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries*

Retrieved from: https://economictimes. indiatimes.com/news/economy/ agriculture/shrimp-productionin-odisha-hit-by-cyclone-fani/ articleshow/69370625.cms?from=mdr

story-12vMmByNipIQwibsJwHJIO.html

[43] Annonymus. Mamata Pegs Cyclone Amphan Damage at Rs. 1 Lakh Crore, Toll Rises to 86. India: The Hindu. 2020. Retrieved from https://www. thehindu.com/news/national/otherstates/mamata-pegs-cyclone-amphandamage-at-1-lakh-crore-toll-rises-to-86/

article31660847.ece

[42] Nandi J, Thakur J. Amphan Transforming into Super Cyclone, first after Deadly 1999 Super Cyclone in Bay of Bengal. Hindustantimes. 2020. Retrieved from https://www. hindustantimes.com/india-news/ amphan-transforming-into-supercyclone-first-after-deadly-1999 super-cyclone-in-bay-of-bengal/

*DOI: http://dx.doi.org/10.5772/intechopen.93784*

[34] Genner MJ, Sims DW, Wearmouth VJ, Southall EJ, Southward AJ, Henderson PA, et al. Regional climatic warming drives long-term community changes of British marine sh. Proceedings of the Royal Society of London, Series B: Biological Sciences. 2004;**271**:655-661

[35] Hooper DU, Chapin FS III,

[36] Sala OE, Chapin FS III,

2000;**287**:1779-1774

Ewel JJ, et al. Effects of biodiversity on ecosystem functioning: A consensus of current knowledge. Ecological Monographs. 2005;**75**:3-35

Armesto JJ, et al. Global biodiversity scenarios for the year 2100. Science.

[37] Stachowicz JJ, Fried H, Osman RW, Whitlatch RB. Biodiversity, invasion resistance, and marine ecosystem function: Reconciling pattern and process. Ecology. 2002;**83**:2575-2590

[38] Bhatia KT, Vecchi GA, Knutson TR, Murakami H, Kossin J, Dixon KW, et al. Recent increases in tropical cyclone intensification rates. Nature Communications. 2019;**10**(1):635

[39] Fitchett J. Why the Indian Ocean is Spawning Strong and Deadly Tropical Cyclones. India: Down To Earth. 2019. Retrieved from: https:// www.downtoearth.org.in/news/ climate-change/why-the-indianocean-is-spawning-strong-and-deadly-

tropical-cyclones-64489

[40] Chhotoray S. Cyclone Fani Took Us 20 Yrs behind, Snatched Our Livelihood': Distressed Chilika Fishermen Await Aid. India: News 18. 2019. Retrieved from: https:// www.news18.com/news/india/ cyclone-fani-has-snatched-ourlivelihood-taken-us-20-years-behindsay-chilika-fishermen-2150891.html

[41] Krishnakumar PK. Shrimp Production in Odisha Hit by Cyclone Fani. The Economic Times. 2019.

*Effect of Climate Change on Aquatic Ecosystem and Production of Fisheries DOI: http://dx.doi.org/10.5772/intechopen.93784*

[34] Genner MJ, Sims DW, Wearmouth VJ, Southall EJ, Southward AJ, Henderson PA, et al. Regional climatic warming drives long-term community changes of British marine sh. Proceedings of the Royal Society of London, Series B: Biological Sciences. 2004;**271**:655-661

*Inland Waters - Dynamics and Ecology*

[18] Orr JC, Fabry VJ, Aumont O, Bopp L, Doney SC, Feely RA, et al. Anthropogenic Ocean acidification over the twenty-first century and its impact on calcifying organisms. Nature. 2005;**437**(7059):681-686. DOI: 10.1038/

[19] Feely RA, Fabry VJ, Guinotte JM. Ocean Acidification of the North Pacific Ocean. Vol. 2. PICES press; 2007. Retrieved from: http://www.pices.int/ publications/pices\_press/volume16/ v16\_n1/pp\_22-26\_Acidification\_f.pdf

[20] Jones GP, McCormick MI, Srinivasan M, Eagle JV. Coral decline threatens fish biodiversity in marine reserves. Proceedings of the National Academy of Sciences.

[21] Grandcourt EM, Cesar HS. The bio-economic impact of mass coral mortality on the coastal reef fisheries of the Seychelles. Fisheries Research.

[22] Parmesan C, Yohe G. A globally coherent fingerprint of climate change impacts across natural systems. Nature. 2003;**421**:37-42. Crossref | CAS |

[23] Peterson AT, Ortega-Huerta MA, Bartley J, Sánchez-Cordero V,

[24] Root TL, Price JT, Hall KR, Schneider SH, Roxenzweiq C,

Soberón J, Buddemeier RH, et al. Future projections for Mexican faunas under global climate change scenarios. Nature.

2004;**101**:8251-8253

2003;**60**(2):539-550

PubMed |

2002;**416**:626-629

2004

science.1085046

nature04095

Pew Center on Global Climate Change;

Pounds JA. Fingerprints of global warming on wild animals and plants.

[26] Thomas CD, Williams SE, Cameron A, et al. Biodiversity

[25] Rosenzweig C, Karoly D, Vicarelli M, et al. Attributing physical and biological impacts to anthropogenic climate change. Nature. 2008;**453**:353-357

conservation: Uncertainty in predictions of extinction risk/effects of changes in climate and land use/climate change and extinction risk. Nature. 2004;**430**:1-2

[27] Macpherson E. Large-scale speciesrichness gradients in the Atlantic Ocean. Proceedings of the Royal Society of London Series B. 2002;**269**:1715-1720

[28] Hiddink JG, Hofstede RT. Climate induced increases in species richness of marine shes. Global Change Biology.

[29] Mueter FJ, Litzow MA. Sea ice retreat alters the biogeography of the Bering Sea continental shelf. Ecological Applications. 2008;**18**(2):309-320

[30] Perry AL, Low PJ, Ellis JR, Reynolds JD. Climate change and distribution shifts in marine shes. Science. 2005;**308**:1912-1915

Ecology. 2008;**45**:1029-1039

British Columbia; 2008

2006;**314**:787-790

[31] Dulvy NK, Rogers SI, Jennings S, Vanessa S, Dye SR, Skjoldal HR. Climate change and deepening of the North Sea sh assemblage: A biotic indicator of warming seas. Journal of Applied

[32] Cheung WWL, Lam VWY, Pauly D. Modelling Present and Climate-Shifted Distribution of Marine Fishes and Invertebrates. Fisheries Centre Research Report 16(3). Vancouver: University of

[33] Worm B, Barbier EB, Beaumont N, et al. Impacts of biodiversity loss on ocean ecosystem services. Science.

2008;**14**:453-460

Nature. 2003;**421**:57-60

[17] Hughes TP, Baird AH, Bellwood DR, Card M, Connolly SR, Folke C, et al. Climate change, human impacts, and the resilience of coral reefs. Science. 2003;**301**(5635):929-933. DOI: 10.1126/

**52**

[35] Hooper DU, Chapin FS III, Ewel JJ, et al. Effects of biodiversity on ecosystem functioning: A consensus of current knowledge. Ecological Monographs. 2005;**75**:3-35

[36] Sala OE, Chapin FS III, Armesto JJ, et al. Global biodiversity scenarios for the year 2100. Science. 2000;**287**:1779-1774

[37] Stachowicz JJ, Fried H, Osman RW, Whitlatch RB. Biodiversity, invasion resistance, and marine ecosystem function: Reconciling pattern and process. Ecology. 2002;**83**:2575-2590

[38] Bhatia KT, Vecchi GA, Knutson TR, Murakami H, Kossin J, Dixon KW, et al. Recent increases in tropical cyclone intensification rates. Nature Communications. 2019;**10**(1):635

[39] Fitchett J. Why the Indian Ocean is Spawning Strong and Deadly Tropical Cyclones. India: Down To Earth. 2019. Retrieved from: https:// www.downtoearth.org.in/news/ climate-change/why-the-indianocean-is-spawning-strong-and-deadlytropical-cyclones-64489

[40] Chhotoray S. Cyclone Fani Took Us 20 Yrs behind, Snatched Our Livelihood': Distressed Chilika Fishermen Await Aid. India: News 18. 2019. Retrieved from: https:// www.news18.com/news/india/ cyclone-fani-has-snatched-ourlivelihood-taken-us-20-years-behindsay-chilika-fishermen-2150891.html

[41] Krishnakumar PK. Shrimp Production in Odisha Hit by Cyclone Fani. The Economic Times. 2019.

Retrieved from: https://economictimes. indiatimes.com/news/economy/ agriculture/shrimp-productionin-odisha-hit-by-cyclone-fani/ articleshow/69370625.cms?from=mdr

[42] Nandi J, Thakur J. Amphan Transforming into Super Cyclone, first after Deadly 1999 Super Cyclone in Bay of Bengal. Hindustantimes. 2020. Retrieved from https://www. hindustantimes.com/india-news/ amphan-transforming-into-supercyclone-first-after-deadly-1999 super-cyclone-in-bay-of-bengal/ story-12vMmByNipIQwibsJwHJIO.html

[43] Annonymus. Mamata Pegs Cyclone Amphan Damage at Rs. 1 Lakh Crore, Toll Rises to 86. India: The Hindu. 2020. Retrieved from https://www. thehindu.com/news/national/otherstates/mamata-pegs-cyclone-amphandamage-at-1-lakh-crore-toll-rises-to-86/ article31660847.ece

**Chapter 4**

**Abstract**

development.

**1. Introduction**

**55**

curve, empirical equations

Designing River Diversion

*Sani Dauda Ahmed, Sampson Kwaku Agodzo*

Quality Improvement

*and Kwaku Amaning Adjei*

Constructed Wetland for Water

Constructed wetlands are recognized as viable potential technology for reducing

pollution load and improving quality of water and wastewater. The use of river diversion wetlands is gaining place for improving quality of river and stream water. However, the design criterion for this category of wetlands has not been fully established, and there is a need to optimize existing approach to enhance operational performance. This chapter presents a step-by-step approach for the design of a typical river diversion constructed wetland intended to remove some pollutants and improve river water quality. The approach focused mainly on water quality objective and outlined simple criteria, guidelines, and model equations for the design procedure of a new river diversion constructed wetland. The design of constructed wetlands is generally an iterative process based on empirical equations. Thus, this approach combines simple equations and procedure for estimating the amount of river water to be diverted for treatment so as to assist the designer in sizing the wetland system. The novel approach presented may be useful to wetland experts as some of the procedures presented are not popular in wetland studies. However, this may improve existing river diversion wetlands' design and

**Keywords:** design, river diversion, constructed wetland, water quality, rating

There is no doubt that streams and rivers are important freshwater sources for man due to their influence on social and economic development of human societies. However, the quality of water in most streams and rivers is being threatened worldwide due to pollution connected with human activities [1]. The situation is worsened with increasing industrial pollution and use of fertilizers and other agrochemicals in agriculture, rapid urbanization, and continuing use of improper sanitation systems especially in developing countries [2]. Consequently, aquatic ecosystems that depend on water flows and seasonal changes within these water bodies are often threatened by poor water quality [3]. Water quality problems represent a major global challenge. For example, pollution of water bodies, especially nutrient loading, has worsened water quality in almost all rivers in Africa, Asia, and Latin

#### **Chapter 4**

## Designing River Diversion Constructed Wetland for Water Quality Improvement

*Sani Dauda Ahmed, Sampson Kwaku Agodzo and Kwaku Amaning Adjei*

#### **Abstract**

Constructed wetlands are recognized as viable potential technology for reducing pollution load and improving quality of water and wastewater. The use of river diversion wetlands is gaining place for improving quality of river and stream water. However, the design criterion for this category of wetlands has not been fully established, and there is a need to optimize existing approach to enhance operational performance. This chapter presents a step-by-step approach for the design of a typical river diversion constructed wetland intended to remove some pollutants and improve river water quality. The approach focused mainly on water quality objective and outlined simple criteria, guidelines, and model equations for the design procedure of a new river diversion constructed wetland. The design of constructed wetlands is generally an iterative process based on empirical equations. Thus, this approach combines simple equations and procedure for estimating the amount of river water to be diverted for treatment so as to assist the designer in sizing the wetland system. The novel approach presented may be useful to wetland experts as some of the procedures presented are not popular in wetland studies. However, this may improve existing river diversion wetlands' design and development.

**Keywords:** design, river diversion, constructed wetland, water quality, rating curve, empirical equations

#### **1. Introduction**

There is no doubt that streams and rivers are important freshwater sources for man due to their influence on social and economic development of human societies. However, the quality of water in most streams and rivers is being threatened worldwide due to pollution connected with human activities [1]. The situation is worsened with increasing industrial pollution and use of fertilizers and other agrochemicals in agriculture, rapid urbanization, and continuing use of improper sanitation systems especially in developing countries [2]. Consequently, aquatic ecosystems that depend on water flows and seasonal changes within these water bodies are often threatened by poor water quality [3]. Water quality problems represent a major global challenge. For example, pollution of water bodies, especially nutrient loading, has worsened water quality in almost all rivers in Africa, Asia, and Latin

America. Therefore, future global water demands cannot be met unless concerted efforts are made to address water quality and wastewater management challenges. a portion of the river flow enters the wetland. On the other hand, in-stream wetlands are constructed within the river bed, and all flows of the river enter into the

Potential benefits of river diversion wetlands include merits relating to river water quality improvement, flood attenuation, increasing connectivity between rivers and floodplains, and creation of mixed habitat of flora and fauna communities [8, 19]. The systems are also cost-effective due to their simple designs and construction when compared to conventional treatment systems. Major drawbacks of these types of wetland systems relate to emissions of greenhouse gases and losses of biodiversity which may result from continued pollution loading [20]. Unlike the in-stream wetlands, a major advantage of the off-stream river diversion wetlands is that they can be used to mitigate non-point source pollution from agricultural lands before reaching the river channel. However, off-stream wetlands may require storage and flow control structures to regulate flow and a large space for layout of the wetlands which may result in high initial costs for land easements. Additionally, only part of the river flow volume can be treated at a time. On the other hand, space availability may not be a big issue for in-stream wetlands as they are constructed within the river bed, and as such the whole river flow volume can be subjected to treatment. However, it may be difficult to regulate flow especially during river peak flows and consequently retention time which is an important aspect of wetland for

*Arrangement of off-stream and in-stream river diversion wetlands. (a) Off-stream river diversion wetland and*

wetland [18]. **Figure 1** shows a typical arrangement of both types.

*Designing River Diversion Constructed Wetland for Water Quality Improvement*

*DOI: http://dx.doi.org/10.5772/intechopen.92119*

effective pollutant removal.

**Figure 1.**

**57**

*(b) in-stream river diversion wetland.*

Therefore, sustainable management of freshwater resources needs to aim at protecting or reducing pollution load of freshwater sources especially streams and rivers to avoid negative impacts on water quality and ecosystems. In this regard, constructed wetlands are recognized as potential technology for meeting water quality and other requirements of these important freshwater sources. The use of constructed wetlands for water quality improvement is increasing with new applications and technological possibilities [4, 5]. In recent times, the use of river diversion wetlands is gaining more relevance for improving quality of water in riverine systems [6–8]. The incorporation of constructed wetlands into management strategies for rivers and streams may help to reduce pollution load and enhance their absorbing capacity against impacts [9].

Despite the recognition of constructed wetlands as an effective and economical way of improving water quality, many of those in operation are underperforming. The shortcomings are partly attributed to limitation and inconsistencies of equations used in designing them [10–12]. Besides, most of the available design methods are either related to municipal wastewater treatment or stormwater quality improvement with the primary aim of peak flow retention to attenuate flood water which may lead to overestimation. For river diversion wetlands, specific design criteria have not been fully established, and further research is needed to optimize existing approach in order to enhance performance capabilities of these types of wetlands [7]. However, the design of constructed wetlands is generally based on empirical equations using zero- or first-order plug flow kinetics as basis for predicting pollutants' removal and improving water quality [13].

This chapter aimed to provide guidance on the design of a typical river diversion constructed wetland intended to improve quality of river water. The chapter provides an overview of factors to be considered for the wetland design, water quality characterization, wetland inflow estimation, computation of the wetland hydrodynamic parameters, wetland sizing, and configuration and guide on designing of conveying and inlet and outlet structures. The approach presented may be useful to wetland experts as some of the procedures adopted are not popular in wetland studies.

#### **2. Types of constructed wetland systems**

Basically, two main types of constructed wetlands exist. These are free water surface (FWS) flow and subsurface flow (SSF) systems. FWS flow wetlands operate with water surface open to the atmosphere, while for SSF, water flow is below the ground through a sand or gravel bed without direct contact with the atmosphere [14, 15]. Both are characterized by shallow basins usually less than 1 m deep. FWS wetlands require more land than SSF wetlands for the same pollution reduction but are easier and cheaper to design and build [16].

FWS flow wetlands are further sub-classified based on the dominant type of vegetation planted in them such as emergent, submerged, or floating aquatic plants. SSF wetlands which are often planted with emergent aquatic plants are best subclassified according to their flow direction as horizontal subsurface flow (HSSF), vertical subsurface flow (VSSF), and hybrid system [17]. Another sub-division of constructed wetland types which have emerged recently is river diversion wetlands. These are mostly FWS wetlands located near or within a stream or river system. They are distinguished according to their location as off-stream and in-stream wetlands. Off-stream wetlands are constructed nearby a river or stream where only

#### *Designing River Diversion Constructed Wetland for Water Quality Improvement DOI: http://dx.doi.org/10.5772/intechopen.92119*

a portion of the river flow enters the wetland. On the other hand, in-stream wetlands are constructed within the river bed, and all flows of the river enter into the wetland [18]. **Figure 1** shows a typical arrangement of both types.

Potential benefits of river diversion wetlands include merits relating to river water quality improvement, flood attenuation, increasing connectivity between rivers and floodplains, and creation of mixed habitat of flora and fauna communities [8, 19]. The systems are also cost-effective due to their simple designs and construction when compared to conventional treatment systems. Major drawbacks of these types of wetland systems relate to emissions of greenhouse gases and losses of biodiversity which may result from continued pollution loading [20]. Unlike the in-stream wetlands, a major advantage of the off-stream river diversion wetlands is that they can be used to mitigate non-point source pollution from agricultural lands before reaching the river channel. However, off-stream wetlands may require storage and flow control structures to regulate flow and a large space for layout of the wetlands which may result in high initial costs for land easements. Additionally, only part of the river flow volume can be treated at a time. On the other hand, space availability may not be a big issue for in-stream wetlands as they are constructed within the river bed, and as such the whole river flow volume can be subjected to treatment. However, it may be difficult to regulate flow especially during river peak flows and consequently retention time which is an important aspect of wetland for effective pollutant removal.

#### **Figure 1.**

*Arrangement of off-stream and in-stream river diversion wetlands. (a) Off-stream river diversion wetland and (b) in-stream river diversion wetland.*

America. Therefore, future global water demands cannot be met unless concerted efforts are made to address water quality and wastewater management challenges. Therefore, sustainable management of freshwater resources needs to aim at protecting or reducing pollution load of freshwater sources especially streams and rivers to avoid negative impacts on water quality and ecosystems. In this regard, constructed wetlands are recognized as potential technology for meeting water quality and other requirements of these important freshwater sources. The use of constructed wetlands for water quality improvement is increasing with new applications and technological possibilities [4, 5]. In recent times, the use of river diversion wetlands is gaining more relevance for improving quality of water in riverine systems [6–8]. The incorporation of constructed wetlands into management strategies for rivers and streams may help to reduce pollution load and

Despite the recognition of constructed wetlands as an effective and economical way of improving water quality, many of those in operation are underperforming. The shortcomings are partly attributed to limitation and inconsistencies of equations used in designing them [10–12]. Besides, most of the available design methods

improvement with the primary aim of peak flow retention to attenuate flood water which may lead to overestimation. For river diversion wetlands, specific design criteria have not been fully established, and further research is needed to optimize existing approach in order to enhance performance capabilities of these types of wetlands [7]. However, the design of constructed wetlands is generally based on empirical equations using zero- or first-order plug flow kinetics as basis for

This chapter aimed to provide guidance on the design of a typical river diversion constructed wetland intended to improve quality of river water. The chapter provides an overview of factors to be considered for the wetland design, water quality characterization, wetland inflow estimation, computation of the wetland hydrodynamic parameters, wetland sizing, and configuration and guide on designing of conveying and inlet and outlet structures. The approach presented may be useful to wetland experts as some of the procedures adopted are not popular in wetland

Basically, two main types of constructed wetlands exist. These are free water surface (FWS) flow and subsurface flow (SSF) systems. FWS flow wetlands operate with water surface open to the atmosphere, while for SSF, water flow is below the ground through a sand or gravel bed without direct contact with the atmosphere [14, 15]. Both are characterized by shallow basins usually less than 1 m deep. FWS wetlands require more land than SSF wetlands for the same pollution reduction but

FWS flow wetlands are further sub-classified based on the dominant type of vegetation planted in them such as emergent, submerged, or floating aquatic plants. SSF wetlands which are often planted with emergent aquatic plants are best subclassified according to their flow direction as horizontal subsurface flow (HSSF), vertical subsurface flow (VSSF), and hybrid system [17]. Another sub-division of constructed wetland types which have emerged recently is river diversion wetlands. These are mostly FWS wetlands located near or within a stream or river system. They are distinguished according to their location as off-stream and in-stream wetlands. Off-stream wetlands are constructed nearby a river or stream where only

are either related to municipal wastewater treatment or stormwater quality

predicting pollutants' removal and improving water quality [13].

**2. Types of constructed wetland systems**

are easier and cheaper to design and build [16].

studies.

**56**

enhance their absorbing capacity against impacts [9].

*Inland Waters - Dynamics and Ecology*

### **3. Design consideration for river diversion constructed wetland**

The design of a constructed river diversion wetland is an iterative process involving site-specific data. Prior to design and construction, site conditions must be evaluated to assess the appropriateness of the site for the proposed constructed wetland system [4]. Thus, the following are recommended as part of the design process:

**3.2 Water quality characterization**

*DOI: http://dx.doi.org/10.5772/intechopen.92119*

applications as opposed to organic pollutants [18].

and includes orthophosphate (PO4

**3.3 Wetland design inflow estimation**

**59**

Characterization of pollutant concentration of the river water to be treated is essential for sizing of a constructed river diversion wetland and in creating a clear understanding of whether the wetland can effectively treat the water or not. Thus, the constituents of the river water and their respective concentrations need to be known before beginning the design process of the constructed river diversion wetland. However, water quality is highly variable especially in rivers due to fluctuations and variability of discharge and contaminant concentration from pollution sources [21]. Thus, a clear definition of water quality is essential, and it may be necessary to take into account previous distribution of the contaminants' concentrations in the water over time [4]. According to [22], characterization of the river water quality can be done based on available data which provides information on temporal and spatial distribution of parameters of interest and their level of concentrations in the water to be treated. Water quality parameters that are characterized in most situations include biochemical oxygen demand (BOD), nitrogen, phosphorus, suspended solids, and coliform bacteria [23]. These are pollutants that originate mostly from organic sources and are considered of most interest in treatment wetland design [24]. Others include metals, phenols, pesticides, and surfactants which may also be treated. However, these parameters require specific

*Designing River Diversion Constructed Wetland for Water Quality Improvement*

BOD reflects the degree of organic matter pollution, and it is a measure of the amount oxygen removed by aerobic microorganisms for their metabolic requirement during decomposition of organic materials. Nitrogen and phosphorus are considered as primary drivers of nutrient pollution, and they occur in organic and inorganic forms. Nitrogen in water is usually measured as total nitrogen, ammonium ion, nitrate, nitrite, and total Kjeldahl nitrogen (sum of organic nitrogen and ammonium ion) or as a combination of these parameters to estimate organic or inorganic nitrogen concentrations [25]. Phosphorus in water is usually measured as total phosphorus which is the sum of organic and inorganic forms of phosphorus

For microbial contamination, indicator organisms are used to detect the presence of pathogens (disease causing organisms). Microorganisms mostly considered are those of fecal origin, and coliform bacteria are most often used to indicate the presence of fecal pollution [26]. Suspended solids are constituents that remain in solid state in water and often occur as part of sediments carried in the water. Measurement of suspended solids is essential as sediments are responsible for contaminant transport in water. Metals can exist as dissolved, colloidal, or suspended forms in water, and their toxicity depends on the degree of oxidation of the metal ion together with the forms in which it occurs [1]. Metals mostly considered with high priority in water pollution are arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), mercury (Hg), nickel (Ni), and zinc (Zn) [23]. Nevertheless, selection of any pollutant or combination of pollutants for water quality improvement will depend on the objectives for which the wetland is designed. Based on the river water quality characterization, appropriate equations can be used to determine the required area and organic loading rates of the wetland system.

The amount of water flow per unit time that passes through a wetland system is

one of the important parameters required in the design of a constructed river diversion wetland. Flow rate of water is an important hydrological parameter required to facilitate sizing of a constructed wetland [4]. Even though flow into a

<sup>3</sup>), polyphosphates, and organic phosphates [1].


#### **3.1 Investigation of site characteristics**

Site condition is a very important factor in the design of a constructed river diversion wetland. This is particularly necessary when a suitable site or land is not readily available as the situation often limits possible options the designer may utilize. Thus, site investigation enables the designer to have an idea of the site characteristics including size of area or land available for the design. However, where there is sufficient suitable site or land, it gives the designer the latitude and flexibility of several design options. Therefore, identifying the required area available for optimal layout of the wetland is vital for effective reduction of pollutants.

Site characteristics to be evaluated when designing and possibly constructing a river diversion wetland include:


After due consideration of the above conditions, a suitable location can be selected for siting the wetland system, and the designer can then take cognizance of the space available for the system design.

#### **3.2 Water quality characterization**

**3. Design consideration for river diversion constructed wetland**

process:

• Investigation of site characteristics

• Wetland design inflow estimation

**3.1 Investigation of site characteristics**

river diversion wetland include:

• Water quality characterization

*Inland Waters - Dynamics and Ecology*

The design of a constructed river diversion wetland is an iterative process involving site-specific data. Prior to design and construction, site conditions must be evaluated to assess the appropriateness of the site for the proposed constructed wetland system [4]. Thus, the following are recommended as part of the design

Site condition is a very important factor in the design of a constructed river diversion wetland. This is particularly necessary when a suitable site or land is not readily available as the situation often limits possible options the designer may utilize. Thus, site investigation enables the designer to have an idea of the site characteristics including size of area or land available for the design. However, where there is sufficient suitable site or land, it gives the designer the latitude and flexibility of several design options. Therefore, identifying the required area available for optimal layout of the wetland is vital for effective reduction of pollutants. Site characteristics to be evaluated when designing and possibly constructing a

• Proximity of the site to the river system (the site should be situated close to the source of water to be treated for easy diversion or within the river channel

• Climate (climate can affect type and size of the space required for the wetland;

• Topography of the land (topographic conditions such as natural depressions and slopes are important consideration; the gradient of the land should preferably have a gentle slope so that water can easily flow by gravity)

• Groundwater condition (assess groundwater levels within the site in different

• Soil and environmental condition of the site (the site should contain soils that can be sufficiently compacted to minimize seepage to groundwater, or necessary measures should be put in place to minimize groundwater contamination)

• Distance of the site from residential buildings to avoid creating an environment

After due consideration of the above conditions, a suitable location can be selected for siting the wetland system, and the designer can then take cognizance of

climatic factors that are important include rainfall, evaporation,

depending on the type (in-stream or off-stream))

evapotranspiration, insolation, and wind velocity)

seasons to guide against possible contamination)

that is not conducive for inhabitants

the space available for the system design.

**58**

Characterization of pollutant concentration of the river water to be treated is essential for sizing of a constructed river diversion wetland and in creating a clear understanding of whether the wetland can effectively treat the water or not. Thus, the constituents of the river water and their respective concentrations need to be known before beginning the design process of the constructed river diversion wetland. However, water quality is highly variable especially in rivers due to fluctuations and variability of discharge and contaminant concentration from pollution sources [21]. Thus, a clear definition of water quality is essential, and it may be necessary to take into account previous distribution of the contaminants' concentrations in the water over time [4]. According to [22], characterization of the river water quality can be done based on available data which provides information on temporal and spatial distribution of parameters of interest and their level of concentrations in the water to be treated. Water quality parameters that are characterized in most situations include biochemical oxygen demand (BOD), nitrogen, phosphorus, suspended solids, and coliform bacteria [23]. These are pollutants that originate mostly from organic sources and are considered of most interest in treatment wetland design [24]. Others include metals, phenols, pesticides, and surfactants which may also be treated. However, these parameters require specific applications as opposed to organic pollutants [18].

BOD reflects the degree of organic matter pollution, and it is a measure of the amount oxygen removed by aerobic microorganisms for their metabolic requirement during decomposition of organic materials. Nitrogen and phosphorus are considered as primary drivers of nutrient pollution, and they occur in organic and inorganic forms. Nitrogen in water is usually measured as total nitrogen, ammonium ion, nitrate, nitrite, and total Kjeldahl nitrogen (sum of organic nitrogen and ammonium ion) or as a combination of these parameters to estimate organic or inorganic nitrogen concentrations [25]. Phosphorus in water is usually measured as total phosphorus which is the sum of organic and inorganic forms of phosphorus and includes orthophosphate (PO4 <sup>3</sup>), polyphosphates, and organic phosphates [1]. For microbial contamination, indicator organisms are used to detect the presence of pathogens (disease causing organisms). Microorganisms mostly considered are those of fecal origin, and coliform bacteria are most often used to indicate the presence of fecal pollution [26]. Suspended solids are constituents that remain in solid state in water and often occur as part of sediments carried in the water. Measurement of suspended solids is essential as sediments are responsible for contaminant transport in water. Metals can exist as dissolved, colloidal, or suspended forms in water, and their toxicity depends on the degree of oxidation of the metal ion together with the forms in which it occurs [1]. Metals mostly considered with high priority in water pollution are arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), mercury (Hg), nickel (Ni), and zinc (Zn) [23]. Nevertheless, selection of any pollutant or combination of pollutants for water quality improvement will depend on the objectives for which the wetland is designed. Based on the river water quality characterization, appropriate equations can be used to determine the required area and organic loading rates of the wetland system.

#### **3.3 Wetland design inflow estimation**

The amount of water flow per unit time that passes through a wetland system is one of the important parameters required in the design of a constructed river diversion wetland. Flow rate of water is an important hydrological parameter required to facilitate sizing of a constructed wetland [4]. Even though flow into a

wetland can be continuous or intermittent, it however passes through the system at low velocities. There are different approaches employed to determine the quantity of inflow (volumetric inflow rate) into a wetland, depending on the wetland type, treatment objectives, and incoming water to be treated.

For wastewater treatment wetlands, inflow is mostly based on wastewater concentration and generation rates [27]. Mass loading charts with reference to the required level of pollutant removal are mostly used in the United States, while in Europe estimation is based on wastewater generation volume and pollutant concentration [27, 28]. For stormwater constructed wetlands, a range of hydrologic methods are applied to estimate design flows. Typical approaches include the use of routing in response to a storm event like the average recurrence interval (ARI) flow criterion, level-pool routing, and estimation of peak runoff flow rate using curve number (CN) model and rational method [29–31]. The ARI is applied in Australia and level-pool in Malaysia, and the CN is mostly used in the United States. While all these methods are mainly applied to stormwater treatment wetlands, they are however used with reference to specific available data and scenarios in these countries [29]. Moreover, not all wetlands are designed for treatment of maximum expected peak flows; otherwise the vegetation are likely to be damaged due to high flows, and the wetland system would need to be extremely large or the outflow water quality requirement considerably relaxed. Furthermore, the CN model has been examined to be inaccurate due to inherent limitation associated with inconsistency of the fixed ratio (λ) between initial abstraction (*Ia*) and soil maximum potential retention (S) in the model [32–34]. The rational method was found to be more suitable only for estimating runoff for relatively small catchment that is preferably less than 50 ha [31]. Besides, paucity of site-specific data especially in Africa can make the use of these methods difficult and inaccurate.

For river diversion wetlands, a specific method for estimating design inflow has not been fully established [7]. However, more recently, [8] evaluated the performance of a river diversion wetland for improving quality of river water using relations that can be used to estimate design inflow for a similar wetland system. These relations are presented below.

$$a = \frac{A\_w}{A\_{rw}}\tag{1}$$

representation that gives relationship between flow regimes and stage heights or water levels of a river at a given site and over a period of time [35, 38]. However, very few rivers have absolutely stable flow characteristics, and thus the rating curve may require revision over time and under unsteady conditions. A comprehensive review of the various equations developed by several authors for correcting

*Designing River Diversion Constructed Wetland for Water Quality Improvement*

Another crucial aspect of wetland design is the estimation of average river flow

• Guide in determining the amount of water per unit time that can be diverted into the wetland system without compromising the flow needed for survival of

• Aid the design and estimation of inflow regime(s) for which the wetland system will be operated since the goal of the wetland is to improve quality of

corresponding to low, moderate, and high flows of the river, respectively. The classification of the flow regimes into low, moderate, and high flows was based on

their computed flow velocities as presented in **Table 1**.

*Typical river rating curve with flows classified into three regimes.*

Therefore, obtaining or developing appropriate rating curve may be necessary to facilitate characterization of flow regimes of the river. Based on the rating curve, the river flows can be classified into low, moderate, and high flows. **Figure 2** shows a typical river rating curve with flows classified into three regimes as indicated. For example, based on the rating curve (**Figure 2**), three flow regimes (0.29 m<sup>3</sup>

For flood or peak flow control wetlands, high flows are often considered for the design, while for water quality improvement, moderate to low flows are mostly the target. Where high flow is to be used for design of river diversion wetland intended for water quality improvement, it may be necessary to include a retention basin in the design to slow down flow energy and allow for gradual release into the system.

/s) (marked with dotted red lines) were selected

/s,

unsteady to steady flow condition was presented by [38].

*3.3.1 Using the rating curve for estimation of river flow regime*

regimes. The river flow regimes are required to:

*DOI: http://dx.doi.org/10.5772/intechopen.92119*

the river ecosystem.

/s, and 3.96 m<sup>3</sup>

river water.

1.97 m<sup>3</sup>

**Figure 2.**

**61**

$$
\rho = \frac{Q\_{w-i}}{Q\_{rd}} \tag{2}
$$

where *α* = wetland/river catchment area ratio; *ω* = wetland/river flow diversion ratio; *Arw* = river catchment area (ha, m<sup>2</sup> ); *Qrd* = average flow volume /discharge in river (m<sup>3</sup> , m<sup>3</sup> per unit time); *Qw*�*<sup>i</sup>* = inflow rate (m<sup>3</sup> /d); *Aw* = proposed area of wetland (m<sup>2</sup> ) based on available space.

Application of the above equations requires estimation of average flow volume of a river. However, flow rates vary over time because of normal variability in precipitation patterns, and a key factor governing hydrological regime of rivers is their discharge variability [35]. Therefore, to determine river flow or discharge regimes, historical flow data are required, including possible seasonality trend of the flows, pattern of past flows (low, moderate, and high flows), and stream gauge information close to the wetland site location [4, 36]. Flow data are important to facilitate understanding of fluctuations in the amount of flowing water in the river and to support development of a rating curve for the river where it is not available. The rating curve has been an important tool widely used for routing purposes in hydrology to estimate discharge in natural rivers [37]. It is a graphical

#### *Designing River Diversion Constructed Wetland for Water Quality Improvement DOI: http://dx.doi.org/10.5772/intechopen.92119*

representation that gives relationship between flow regimes and stage heights or water levels of a river at a given site and over a period of time [35, 38]. However, very few rivers have absolutely stable flow characteristics, and thus the rating curve may require revision over time and under unsteady conditions. A comprehensive review of the various equations developed by several authors for correcting unsteady to steady flow condition was presented by [38].

#### *3.3.1 Using the rating curve for estimation of river flow regime*

Another crucial aspect of wetland design is the estimation of average river flow regimes. The river flow regimes are required to:


Therefore, obtaining or developing appropriate rating curve may be necessary to facilitate characterization of flow regimes of the river. Based on the rating curve, the river flows can be classified into low, moderate, and high flows. **Figure 2** shows a typical river rating curve with flows classified into three regimes as indicated. For example, based on the rating curve (**Figure 2**), three flow regimes (0.29 m<sup>3</sup> /s, 1.97 m<sup>3</sup> /s, and 3.96 m<sup>3</sup> /s) (marked with dotted red lines) were selected corresponding to low, moderate, and high flows of the river, respectively. The classification of the flow regimes into low, moderate, and high flows was based on their computed flow velocities as presented in **Table 1**.

For flood or peak flow control wetlands, high flows are often considered for the design, while for water quality improvement, moderate to low flows are mostly the target. Where high flow is to be used for design of river diversion wetland intended for water quality improvement, it may be necessary to include a retention basin in the design to slow down flow energy and allow for gradual release into the system.

**Figure 2.** *Typical river rating curve with flows classified into three regimes.*

wetland can be continuous or intermittent, it however passes through the system at low velocities. There are different approaches employed to determine the quantity of inflow (volumetric inflow rate) into a wetland, depending on the wetland type,

For wastewater treatment wetlands, inflow is mostly based on wastewater con-

centration and generation rates [27]. Mass loading charts with reference to the required level of pollutant removal are mostly used in the United States, while in Europe estimation is based on wastewater generation volume and pollutant concentration [27, 28]. For stormwater constructed wetlands, a range of hydrologic methods are applied to estimate design flows. Typical approaches include the use of routing in response to a storm event like the average recurrence interval (ARI) flow criterion, level-pool routing, and estimation of peak runoff flow rate using curve number (CN) model and rational method [29–31]. The ARI is applied in Australia and level-pool in Malaysia, and the CN is mostly used in the United States. While all these methods are mainly applied to stormwater treatment wetlands, they are however used with reference to specific available data and scenarios in these countries [29]. Moreover, not all wetlands are designed for treatment of maximum expected peak flows; otherwise the vegetation are likely to be damaged due to high flows, and the wetland system would need to be extremely large or the outflow water quality requirement considerably relaxed. Furthermore, the CN model has been examined to be inaccurate due to inherent limitation associated with inconsistency of the fixed ratio (λ) between initial abstraction (*Ia*) and soil maximum potential retention (S) in the model [32–34]. The rational method was found to be more suitable only for estimating runoff for relatively small catchment that is preferably less than 50 ha [31]. Besides, paucity of site-specific data especially in

Africa can make the use of these methods difficult and inaccurate.

, m<sup>3</sup> per unit time); *Qw*�*<sup>i</sup>* = inflow rate (m<sup>3</sup>

hydrology to estimate discharge in natural rivers [37]. It is a graphical

) based on available space.

These relations are presented below.

ratio; *Arw* = river catchment area (ha, m<sup>2</sup>

river (m<sup>3</sup>

**60**

wetland (m<sup>2</sup>

For river diversion wetlands, a specific method for estimating design inflow has not been fully established [7]. However, more recently, [8] evaluated the performance of a river diversion wetland for improving quality of river water using relations that can be used to estimate design inflow for a similar wetland system.

> *<sup>α</sup>* <sup>¼</sup> *Aw Arw*

*<sup>ω</sup>* <sup>¼</sup> *Qw*�*<sup>i</sup> Qrd*

where *α* = wetland/river catchment area ratio; *ω* = wetland/river flow diversion

Application of the above equations requires estimation of average flow volume of a river. However, flow rates vary over time because of normal variability in precipitation patterns, and a key factor governing hydrological regime of rivers is their discharge variability [35]. Therefore, to determine river flow or discharge regimes, historical flow data are required, including possible seasonality trend of the flows, pattern of past flows (low, moderate, and high flows), and stream gauge information close to the wetland site location [4, 36]. Flow data are important to facilitate understanding of fluctuations in the amount of flowing water in the river and to support development of a rating curve for the river where it is not available. The rating curve has been an important tool widely used for routing purposes in

(1)

(2)

); *Qrd* = average flow volume /discharge in

/d); *Aw* = proposed area of

treatment objectives, and incoming water to be treated.

*Inland Waters - Dynamics and Ecology*


#### **Table 1.**

*Classification of the flow regimes.*

Since the river diversion wetland under discussion is intended to be designed for water quality improvement, only a portion of the river flow regimes is required to be diverted into the wetland system per unit time. Thus, to determine the quantity of the design inflow rate of the wetland, Eq. (3) derived from Eqs. (1) and (2) can be used together with the average river flow regime(s).

$$Q\_{w-i} = \frac{A\_w Q\_{rd}}{A\_{rc}}\tag{3}$$

*Ce Ci* ¼ *e*

*Designing River Diversion Constructed Wetland for Water Quality Improvement*

*KT* ¼ *KRθ<sup>R</sup>*

*Tw* = ambient or water temperature (°C).

*DOI: http://dx.doi.org/10.5772/intechopen.92119*

(m/d); *Qw*�*<sup>i</sup>* = inflow rate (m3

presented below:

where *Ce* = outflow pollutant concentration (mg/l); *Ci* = inflow pollutant concentration (mg/l); *t* = nominal hydraulic residence or retention time (d); *KT* = reaction rate constant for BOD at *Tw* (/d); *KR* = rate constant at *TR* (/day); *θ<sup>R</sup>* = temperature coefficient for rate constant; *TR* = reference temperature (°C);

The area-based model equation was developed by [44], and the equations are

*hl* <sup>¼</sup> *Qw*�*<sup>i</sup> Aw*

where *C*<sup>∗</sup> = background pollutant concentration (mg/l); *Kl* = reaction rate constant for phosphorus and fecal coliform (m/d); *hl* = hydraulic loading rate

The volume-based model was developed based on those parameters that are removed primarily by biological processes such as biochemical oxygen demand (BOD), ammonia (NH4), and nitrate (NO3). The areal equation considered more parameters and in addition includes total suspended solids (TSS), total phosphorus (TP), total nitrogen (TN), and fecal coliform (FC). According to [45], while the [43] method provides a relatively conservative area estimate, [44] approach may require considerable land space, depending on the pollutant concentration limit. Furthermore, the [45] model appears to be less sensitive to different climatic conditions as temperature changes are only considered significant for nitrogen removal [46]. However, temperature plays an important role in constructed wetland systems as it enhances higher biological activity and productivity which may lead to better performance of the systems [47, 48]. For this reason, the use of these models may lead to wide variations in performance due to effect of changes in climatic conditions. Additionally, many authors have developed more complex models like the Monod-type and mechanistic compartmental models [49, 50]. However, the [43, 44] models appear to be more straightforward and can be applied with ease by wetland designers [13]. Data limitation on operational performance of constructed wetlands prevented the development of equations which can clearly describe the kinetics of known wetland processes [23]. Thus, optimal design of constructed wetland systems has not yet been determined. However, in order to take advantage of [43, 44] models and ease complexity of computation, [24] presented a simplified approach for the design and sizing of FWS constructed wetlands using the two equations. The approach was based on performance criteria for the removal of four water quality parameters that included BOD, nitrogen, phosphorus, and coliform bacteria. According to [24], rates of BOD and nitrogen removal are principally temperature dependent and therefore utilized equations proposed by [43] model for removal of these parameters. On the other hand, the reduction of phosphorus and coliform bacteria was assumed to be governed by physical processes which are less temperature-dependent, and thus [44] equations were used. In addition, [24, 51] proposed the following relationships for nominal hydraulic retention time

available space and other parameters as defined in Eq. (1).

and removal of total nitrogen (TN), respectively.

**63**

�*Kl*

/d); *Aw* = proposed area of wetland (m<sup>2</sup>

*Ce* � *<sup>C</sup>*<sup>∗</sup> *Ci* � *<sup>C</sup>*<sup>∗</sup> <sup>¼</sup> *<sup>e</sup>*

�*KTt* (4)

ð Þ *Tw*�*TR* (5)

*hl* (6)

(7)

) based on

where all parameters remain the same as previously defined in Eqs. (1) and (2).

The wetland can be designed to operate with the three river flow regimes (low, moderate, and high) to take into account seasonal flow variability or a single flow regime depending on the objective and availability of space within the site.

#### **4. Computing hydrodynamic parameters of the wetland**

#### **4.1 Wetland design equations**

The design of constructed wetlands is generally based on empirical equations using zero- or first-order plug flow kinetics as basis for predicting pollutant removal and improving water quality [13]. With zero-order kinetics, the reaction rate does not change with concentration but varies with temperature [4], while first-order kinetics simply implies that the rate of removal of a particular pollutant is directly proportional to the remaining concentration of the pollutant at any point within the wetland [40]. Plug flow means that every portion of flow entering into the wetland takes almost the same amount of time to pass through it which is rarely the case [41]. The kinetic equations also considered FWS wetlands as attached growth biological reactors similar to those found in conventional wastewater treatment systems [23]. Generally, two types of equations are popular that use two different approaches in the design of FWS wetlands based on "rule-of-thumb" (no account for the many complex reactions that occur in a constructed wetland). There is the volume-based or zero-order kinetic equation which uses hydraulic retention time to optimize pollutant removal [42, 43]. The second is the area-based or first-order kinetic equation where the entire wetland area is used to provide the desired pollutant treatment [44]. The key difference between the two equations is in the use of kinetic rate constants. Volume-based equation assumes horizontal or linear kinetics and uses volumetric and temperature-dependent rate constant, with calculations being based on available volume of the wetland and average water temperature. The area-based equation assumes vertical or areal kinetics and uses rate constants which are independent of temperature but related to the wetland surface area. The volume-based equation was developed by [43], and the equations are presented below:

*Designing River Diversion Constructed Wetland for Water Quality Improvement DOI: http://dx.doi.org/10.5772/intechopen.92119*

$$\frac{C\_{\epsilon}}{C\_{i}} = e^{-K\_{T}t} \tag{4}$$

$$K\_T = K\_R \theta\_R^{(T\_w - T\_R)} \tag{5}$$

where *Ce* = outflow pollutant concentration (mg/l); *Ci* = inflow pollutant concentration (mg/l); *t* = nominal hydraulic residence or retention time (d); *KT* = reaction rate constant for BOD at *Tw* (/d); *KR* = rate constant at *TR* (/day); *θ<sup>R</sup>* = temperature coefficient for rate constant; *TR* = reference temperature (°C); *Tw* = ambient or water temperature (°C).

The area-based model equation was developed by [44], and the equations are presented below:

$$\frac{\mathbf{C}\_{\epsilon} - \mathbf{C}^\*}{\mathbf{C}\_{l} - \mathbf{C}^\*} = e^{-\frac{K\_l}{k\_l}} \tag{6}$$

$$h\_l = \frac{Q\_{w-i}}{A\_w} \tag{7}$$

where *C*<sup>∗</sup> = background pollutant concentration (mg/l); *Kl* = reaction rate constant for phosphorus and fecal coliform (m/d); *hl* = hydraulic loading rate (m/d); *Qw*�*<sup>i</sup>* = inflow rate (m3 /d); *Aw* = proposed area of wetland (m<sup>2</sup> ) based on available space and other parameters as defined in Eq. (1).

The volume-based model was developed based on those parameters that are removed primarily by biological processes such as biochemical oxygen demand (BOD), ammonia (NH4), and nitrate (NO3). The areal equation considered more parameters and in addition includes total suspended solids (TSS), total phosphorus (TP), total nitrogen (TN), and fecal coliform (FC). According to [45], while the [43] method provides a relatively conservative area estimate, [44] approach may require considerable land space, depending on the pollutant concentration limit. Furthermore, the [45] model appears to be less sensitive to different climatic conditions as temperature changes are only considered significant for nitrogen removal [46]. However, temperature plays an important role in constructed wetland systems as it enhances higher biological activity and productivity which may lead to better performance of the systems [47, 48]. For this reason, the use of these models may lead to wide variations in performance due to effect of changes in climatic conditions. Additionally, many authors have developed more complex models like the Monod-type and mechanistic compartmental models [49, 50]. However, the [43, 44] models appear to be more straightforward and can be applied with ease by wetland designers [13]. Data limitation on operational performance of constructed wetlands prevented the development of equations which can clearly describe the kinetics of known wetland processes [23]. Thus, optimal design of constructed wetland systems has not yet been determined. However, in order to take advantage of [43, 44] models and ease complexity of computation, [24] presented a simplified approach for the design and sizing of FWS constructed wetlands using the two equations. The approach was based on performance criteria for the removal of four water quality parameters that included BOD, nitrogen, phosphorus, and coliform bacteria. According to [24], rates of BOD and nitrogen removal are principally temperature dependent and therefore utilized equations proposed by [43] model for removal of these parameters. On the other hand, the reduction of phosphorus and coliform bacteria was assumed to be governed by physical processes which are less temperature-dependent, and thus [44] equations were used. In addition, [24, 51] proposed the following relationships for nominal hydraulic retention time and removal of total nitrogen (TN), respectively.

Since the river diversion wetland under discussion is intended to be designed for water quality improvement, only a portion of the river flow regimes is required to be diverted into the wetland system per unit time. Thus, to determine the quantity of the design inflow rate of the wetland, Eq. (3) derived from Eqs. (1) and (2) can

> *Qw*�*<sup>i</sup>* <sup>¼</sup> *AwQrd Arc*

The design of constructed wetlands is generally based on empirical equations using zero- or first-order plug flow kinetics as basis for predicting pollutant removal and improving water quality [13]. With zero-order kinetics, the reaction rate does not change with concentration but varies with temperature [4], while first-order kinetics simply implies that the rate of removal of a particular pollutant is directly proportional to the remaining concentration of the pollutant at any point within the wetland [40]. Plug flow means that every portion of flow entering into the wetland takes almost the same amount of time to pass through it which is rarely the case [41]. The kinetic equations also considered FWS wetlands as attached growth biological reactors similar to those found in conventional wastewater treatment systems [23]. Generally, two types of equations are popular that use two different approaches in the design of FWS wetlands based on "rule-of-thumb" (no account for the many complex reactions that occur in a constructed wetland). There is the volume-based or zero-order kinetic equation which uses hydraulic retention time to optimize pollutant removal [42, 43]. The second is the area-based or first-order kinetic equation where the entire wetland area is used to provide the desired pollutant treatment [44]. The key difference between the two equations is in the use of kinetic rate constants. Volume-based equation assumes horizontal or linear kinetics and uses volumetric and temperature-dependent rate constant, with calculations being based on available volume of the wetland and average water temperature. The area-based equation assumes vertical or areal kinetics and uses rate constants which are independent of temperature but related to the wetland surface area. The volume-based equation was

where all parameters remain the same as previously defined in Eqs. (1) and (2). The wetland can be designed to operate with the three river flow regimes (low, moderate, and high) to take into account seasonal flow variability or a single flow regime depending on the objective and availability of space within the site.

(3)

be used together with the average river flow regime(s).

**Mean cross-sectional area of river gauging section (m<sup>2</sup>**

**)**

0.29 3.34 0.09 <0.10 Low flow 1.97 3.34 0.59 0.10–0.60 Moderate flow 3.96 3.34 1.19 ≥0.70 High flow

**Velocity (m/s)**

**Velocity\* groups (m/s)**

**Classification**

**4. Computing hydrodynamic parameters of the wetland**

developed by [43], and the equations are presented below:

**4.1 Wetland design equations**

**Flow regimes (m<sup>3</sup> /s)**

**Table 1.**

**62**

*\*Values of velocity groups adapted from [39].*

*Inland Waters - Dynamics and Ecology*

*Classification of the flow regimes.*

$$t = \frac{V\_{w-n}}{Q\_{w-i}} = \frac{A\_w \chi\_w \mathcal{Q}}{Q\_{w-i}} = \frac{\chi\_w \mathcal{Q}}{h\_l} \tag{8}$$

phosphorus, and coliform bacteria), often used for sizing of constructed wetlands. **Table 2** shows the parameters and kinetic equation used for determining the

*Designing River Diversion Constructed Wetland for Water Quality Improvement*

The HLR of the wetlands system can be computed using Eq. (7) by [44]. The determination of the HLR is essential to guide in the design and can assist to avoid overloading the system. Thus, the design may confirm the organic loading rate is within the wetland limit; an equation developed by [51] can be used to compare the

*KT* <sup>≤</sup> �10 In *Ce*

where all parameters remain the same as defined in Eqs. (1), (2), and (4).

Sizing is an important component of wetland design and vital for pollutant removal processes to take place. Most of the design recommendations provided certain approaches to wetland sizing to maximize removal of pollutants. For wastewater treatment wetlands, population equivalent (PE) is mostly employed for the determination of design wetland area. The required surface area is usually expressed

the type (HSSF, VSF, and hybrids) [27]. For stormwater wetlands, the typical approach is to consider relative percentage of the contributing catchment area or

recommended as actual sizing criterion [4]. For full-scale river diversion wetlands, a minimum of 2–7% of the total catchment area was recommended as wetland area [20]. However, such sizing criteria pose challenges of overestimation and do not account for any performance consideration [53]. Therefore, such prescribed wetland sizing criteria may be unrealistic due to space limitation and cost. Nevertheless, an approach derived based on empirical determination of actual area required for pollutant removal with reference to hydraulic loading rate as presented by [24] appears to be more realistic for estimating actual area of river diversion wetlands intended for water quality improvement. Thus, the actual area required for such a wetland system

connected impervious area, and 1–5% of the contributing watershed was

can be determined using Eq. (16) which was derived from Eq. (8) by [24].

where *Awc* = actual area of the wetland (m<sup>2</sup>

Eq. (8).

**65**

*Awc* <sup>¼</sup> *Qw*�*<sup>i</sup> <sup>t</sup>*

For ease of operational control (flow control and water level adjustment) and increased removal efficiency, multiple wetland units often referred to as cells may be used where possible than a single unit wetland. This is particularly more applicable to design of off-stream river diversion wetland. Multiple cells have the advantages of providing greater flexibility in design and operation and enhancing the performance of the system by decreasing the potential for short-circuiting.

recommended for FWS, while for SSF it ranges between 2 and 5 m2

*=Ci* 

*Ciyw*<sup>∅</sup> (10)

/PE). For example, 5–10 m2

*yw*<sup>∅</sup> (11)

) and other parameters as defined in

/PE was

/PE depending on

*KT* value with the loading rate. The equation is presented as:

nominal HRT.

*4.2.2 Hydraulic loading rate (HLR)*

*DOI: http://dx.doi.org/10.5772/intechopen.92119*

**5. Wetland sizing and configuration**

as unit area per population equivalent (m2

$$\frac{\mathbf{C}\_{\epsilon}}{\mathbf{C}\_{i}} = e^{-K\_{\mathrm{TD}^{\mathrm{f}}}} + e^{K\_{\mathrm{TD}^{\mathrm{f}}}} - e^{K\_{\mathrm{TD}^{\mathrm{f}}}}e^{K\_{\mathrm{TD}^{\mathrm{f}}}} \tag{9}$$

where *Vw*�*<sup>n</sup>* = wetland nominal volume (m3 ); *yw* = theoretical or nominal depth of wetland water flow (m); ∅ = porosity (percent, expressed as decimal fraction); *KTD* = reaction rate constant for denitrification (/d); *KTN* = reaction rate constant for nitrification (/d) and other parameters as defined in Eqs. (1), (3), and (4).

The authors recommended that the above equations can be used together with those presented by [43, 44] to determine the hydrodynamic and size parameters of a new FWS flow constructed wetland, depending on the target pollutant or combination of pollutants (BOD, nitrogen, phosphorus, and coliform bacteria) required to be removed from the wastewater. As indicated by [52], the approach presented by [24] is useful in the design of a new FWS constructed wetland and for performance evaluation of existing ones.

#### **4.2 Using a combination of equations for river diversion wetlands**

The use of a combination of wetland design equations proposed by [24, 51] was found to be useful for determination of river diversion wetlands' hydrodynamic parameters. These parameters include nominal hydraulic retention time and hydraulic loading rate.

#### *4.2.1 Hydraulic retention time (HRT)*

Determination of nominal hydraulic retention time is important for design guide and estimating possible pollutant removal ability of the wetland system. Thus, the nominal HRT for a river diversion wetland can be estimated based on the kinetic equations governing the removal of basic water quality parameters (BOD, nitrogen,


*Note: Kl = reaction rate constant for TP = 0.0273 m/d and FC = 0.3 m/d);* ∅ *= porosity or space available for water flow through vegetation (0.65–0.75); Tw= water or ambient temperature.*

#### **Table 2.**

*Parameters and equations for computing design HRT.*

*Designing River Diversion Constructed Wetland for Water Quality Improvement DOI: http://dx.doi.org/10.5772/intechopen.92119*

phosphorus, and coliform bacteria), often used for sizing of constructed wetlands. **Table 2** shows the parameters and kinetic equation used for determining the nominal HRT.

#### *4.2.2 Hydraulic loading rate (HLR)*

*<sup>t</sup>* <sup>¼</sup> *Vw*�*<sup>n</sup> Qw*�*<sup>i</sup>*

�*KTNt* <sup>þ</sup> *<sup>e</sup>*

**4.2 Using a combination of equations for river diversion wetlands**

The use of a combination of wetland design equations proposed by [24, 51] was found to be useful for determination of river diversion wetlands' hydrodynamic parameters. These parameters include nominal hydraulic retention time and

Determination of nominal hydraulic retention time is important for design guide and estimating possible pollutant removal ability of the wetland system. Thus, the nominal HRT for a river diversion wetland can be estimated based on the kinetic equations governing the removal of basic water quality parameters (BOD, nitrogen,

**Parameter Empirical equations Equation no. Source**

*KTN* <sup>¼</sup> <sup>0</sup>*:*2187 1ð Þ *:*<sup>048</sup> *Tw*�<sup>20</sup> (12) *KTD* <sup>¼</sup> ð Þ <sup>1</sup>*:*<sup>048</sup> *Tw*�<sup>20</sup> (13)

*Ci* <sup>¼</sup> *<sup>e</sup>*�*KTN <sup>t</sup>* <sup>þ</sup> *eKTDt* � *<sup>e</sup>KTN <sup>t</sup>*

*Ci* ¼ *e Kl*

*<sup>t</sup>* <sup>¼</sup> *<sup>y</sup>*<sup>∅</sup> *hl*

*Ci* ¼ *e Kl*

*<sup>t</sup>* <sup>¼</sup> *<sup>y</sup>*<sup>∅</sup> *hl*

*Note: Kl = reaction rate constant for TP = 0.0273 m/d and FC = 0.3 m/d);* ∅ *= porosity or space available for water*

*Ci* <sup>¼</sup> *<sup>e</sup>*�*KT <sup>t</sup>* (1) [41]

*eKTDt* (9) [12]

(14) [13]

(14) [13]

*hl* (10) [22]

*hl* (10) [22]

*KT* <sup>¼</sup> <sup>0</sup>*:*678 1ð Þ *:*<sup>06</sup> *Tw*�<sup>20</sup> (11) [12]

*Ce Ci* ¼ *e*

where *Vw*�*<sup>n</sup>* = wetland nominal volume (m3

*Inland Waters - Dynamics and Ecology*

evaluation of existing ones.

hydraulic loading rate.

*4.2.1 Hydraulic retention time (HRT)*

BOD (mg/l) *Ce*

TP (mg/l) *Ce*

FC (CFU/100 ml) *Ce*

*Parameters and equations for computing design HRT.*

*flow through vegetation (0.65–0.75); Tw= water or ambient temperature.*

TN (mg/l) *Ce*

**Table 2.**

**64**

<sup>¼</sup> *Awyw*<sup>∅</sup> *Qw*�*<sup>i</sup>*

of wetland water flow (m); ∅ = porosity (percent, expressed as decimal fraction); *KTD* = reaction rate constant for denitrification (/d); *KTN* = reaction rate constant for nitrification (/d) and other parameters as defined in Eqs. (1), (3), and (4). The authors recommended that the above equations can be used together with those presented by [43, 44] to determine the hydrodynamic and size parameters of a new FWS flow constructed wetland, depending on the target pollutant or combination of pollutants (BOD, nitrogen, phosphorus, and coliform bacteria) required to be removed from the wastewater. As indicated by [52], the approach presented by [24] is useful in the design of a new FWS constructed wetland and for performance

*KTDt* � *<sup>e</sup>*

<sup>¼</sup> *yw*<sup>∅</sup> *hl*

*KTNt e* (8)

*KTDt* (9)

); *yw* = theoretical or nominal depth

The HLR of the wetlands system can be computed using Eq. (7) by [44]. The determination of the HLR is essential to guide in the design and can assist to avoid overloading the system. Thus, the design may confirm the organic loading rate is within the wetland limit; an equation developed by [51] can be used to compare the *KT* value with the loading rate. The equation is presented as:

$$K\_T \le \frac{-10\text{ In}\left(\text{c}\swarrow\_{\text{\tiny{<}}}\right)}{\text{C}\_{\text{i}}\text{y}\_w\mathcal{D}}\tag{10}$$

where all parameters remain the same as defined in Eqs. (1), (2), and (4).

#### **5. Wetland sizing and configuration**

Sizing is an important component of wetland design and vital for pollutant removal processes to take place. Most of the design recommendations provided certain approaches to wetland sizing to maximize removal of pollutants. For wastewater treatment wetlands, population equivalent (PE) is mostly employed for the determination of design wetland area. The required surface area is usually expressed as unit area per population equivalent (m2 /PE). For example, 5–10 m2 /PE was recommended for FWS, while for SSF it ranges between 2 and 5 m2 /PE depending on the type (HSSF, VSF, and hybrids) [27]. For stormwater wetlands, the typical approach is to consider relative percentage of the contributing catchment area or connected impervious area, and 1–5% of the contributing watershed was recommended as actual sizing criterion [4]. For full-scale river diversion wetlands, a minimum of 2–7% of the total catchment area was recommended as wetland area [20]. However, such sizing criteria pose challenges of overestimation and do not account for any performance consideration [53]. Therefore, such prescribed wetland sizing criteria may be unrealistic due to space limitation and cost. Nevertheless, an approach derived based on empirical determination of actual area required for pollutant removal with reference to hydraulic loading rate as presented by [24] appears to be more realistic for estimating actual area of river diversion wetlands intended for water quality improvement. Thus, the actual area required for such a wetland system can be determined using Eq. (16) which was derived from Eq. (8) by [24].

$$A\_{w\circ} = \frac{Q\_{w-i}\,t}{\mathcal{Y}\_w \mathcal{Q}}\tag{11}$$

where *Awc* = actual area of the wetland (m<sup>2</sup> ) and other parameters as defined in Eq. (8).

For ease of operational control (flow control and water level adjustment) and increased removal efficiency, multiple wetland units often referred to as cells may be used where possible than a single unit wetland. This is particularly more applicable to design of off-stream river diversion wetland. Multiple cells have the advantages of providing greater flexibility in design and operation and enhancing the performance of the system by decreasing the potential for short-circuiting.

Wetland cell size depends primarily on water quality treatment needs and cost considerations.

The actual area of the wetland is then computed using Eq. (16). Based on the computed values, the actual area of the wetland is thus selected as the maximum of areas obtained for each of the target pollutants (BOD, nitrogen, phosphorus, and coliform bacteria).

the secondary is to act as a spillway and control flows in excess of the maximum design flow regime. Different types of control structures are available that can be used to control water level within the wetland. These may include number of individual pipes that fit together in a combination to obtain the desired water level, drop structures, or weirs. The design requirements of drop control structures and weirs can be found in hydraulic books. The outlet or water level control structure should be able to completely dewater the wetland when needed and allow for

*Designing River Diversion Constructed Wetland for Water Quality Improvement*

The management and restoration of water bodies like rivers should go beyond protection through the use of regulations. It should also make the most of opportunities that arise from using ecosystem properties to enhance self-purification capacity of rivers for water quality improvement. A key consideration is the use of

This chapter provided guidance on the design of a river diversion constructed wetland aimed at improving quality of river water. The use of a combination of empirical equations was presented to guide in the estimation of the actual wetland area rather than relying on an assumed rate. The design approach using these equations may present a promising method for the design of river diversion wetlands. Furthermore, this novel approach may be useful to wetland experts as some of the procedures adopted are not popular in wetland studies. This may provide opportunity for wetland designers to document approaches that have been found promising and come up with suitable design criteria for constructed river diversion

The authors wish to express appreciation for the funding support provided by the Regional Water and Environmental Sanitation Centre, Kumasi (RWESCK), at the Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, which is funded by the Government of Ghana and the World Bank under the Africa Centres of Excellence Project. Also, the authors wish to thank the National Water Resources Institute (NWRI), Nigeria, for providing opportunity and support for the study that led to the generation of knowledge and information presented in this chapter. We declare that the views expressed in this chapter are those of the authors and do not necessarily reflect those of the World Bank, Ghana Government,

changes to be made easily.

constructed river diversion wetlands.

*DOI: http://dx.doi.org/10.5772/intechopen.92119*

**7. Conclusion**

wetlands.

**Acknowledgements**

KNUST, and NWRI.

**Conflict of interest**

None declared.

**67**

Wetland system configuration is an important element in the design of river diversion constructed wetland technology. After determining an appropriate wetland size, it is necessary to define the system configuration or layout by choosing an appropriate aspect ratio. Aspect ratio represents length (L) to width (W) ratio (L/W) of the wetland. It was suggested that choosing a good aspect ratio can assist to minimize short-circuiting and maximize flow distribution within the wetland system for biological activities [54]. Aspect ratio of as low as 1:1 was recommended for SSF [55], while length to width ratio of between 3:1 and 5:1 was recommended for FWS from an optimal point of view by [23]. However, based on findings by [56], 10:1 was recommended for FWS for good hydraulic efficiency. For water quality improvement, a river diversion wetland should be designed to operate with the most efficient aspect ratio.

Wetland bed slopes are also critical to maintain a uniform water depth throughout the wetland system and facilitate drainage. In order to minimize shortcircuiting, a uniform bed slope from inlet to outlet is recommended. Thus, the bed slope for SSF should be 2% or less, while that for FWS should be 0.5% or less [14]. A river diversion wetland can also be designed to operate with similar bed slope as recommended for FWS since they are related in mode of operation.

#### **6. Water conveying system: inlet and outlet structures of the wetland**

This aspect of the wetland design focused on selecting or designing a water conveying system, inlet and outlet control structures that can facilitate flow and distribute inflow and drain outflow water from the wetland effectively. Depending on the type of river diversion wetland, flow diversion structure may be designed to consist of either a pipe or channel system and should function to provide a controlled flow of water to the wetland. However, it is necessary to be explicit about flow capacity at the time of design so that appropriate sizing of flow diversion structure can be made. Generally, the design flow conveyance structure is based on hydraulic; therefore the reader is referred to hydraulic books for detailed information.

In order to ensure that the inflow water is uniformly distributed across the entire wetland area, multiple entry openings or gates should be considered rather than single to deliver the range of design flow regimes required. Flow control structures should be used to control inflow rate and maintain water levels. Control valves or weirs or a combination can be used depending on the type of inlet structured selected. Since the wetland system is for water quality improvement, high incoming water velocities should be discouraged. Therefore, energy dissipation system may be required for the incoming water to provide protection for the wetland inlet. The inlet openings should be designed large enough to avoid obstruction. Inlet zones should provide access for sampling and flow monitoring.

Wetland outlet design is essential in avoiding possible dead zones and controlling water level and for monitoring flow and water quality. Depending on the size of the wetland, a combination of outlets (primary and secondary) or multiple outlets consisting of hydraulic control structures can be considered to collect and discharge treated water for the range of design flow regimes and maintain required water storage level. The purpose of the primary outlets is for water quality control, while

*Designing River Diversion Constructed Wetland for Water Quality Improvement DOI: http://dx.doi.org/10.5772/intechopen.92119*

the secondary is to act as a spillway and control flows in excess of the maximum design flow regime. Different types of control structures are available that can be used to control water level within the wetland. These may include number of individual pipes that fit together in a combination to obtain the desired water level, drop structures, or weirs. The design requirements of drop control structures and weirs can be found in hydraulic books. The outlet or water level control structure should be able to completely dewater the wetland when needed and allow for changes to be made easily.

#### **7. Conclusion**

Wetland cell size depends primarily on water quality treatment needs and cost

The actual area of the wetland is then computed using Eq. (16). Based on the computed values, the actual area of the wetland is thus selected as the maximum of areas obtained for each of the target pollutants (BOD, nitrogen, phosphorus, and

Wetland system configuration is an important element in the design of river diversion constructed wetland technology. After determining an appropriate wetland size, it is necessary to define the system configuration or layout by choosing an appropriate aspect ratio. Aspect ratio represents length (L) to width (W) ratio (L/W) of the wetland. It was suggested that choosing a good aspect ratio can assist to minimize short-circuiting and maximize flow distribution within the wetland system for biological activities [54]. Aspect ratio of as low as 1:1 was recommended for SSF [55], while length to width ratio of between 3:1 and 5:1 was recommended for FWS from an optimal point of view by [23]. However, based on findings by [56], 10:1 was recommended for FWS for good hydraulic efficiency. For water quality improvement, a river diversion wetland should be designed to operate with

Wetland bed slopes are also critical to maintain a uniform water depth through-

circuiting, a uniform bed slope from inlet to outlet is recommended. Thus, the bed slope for SSF should be 2% or less, while that for FWS should be 0.5% or less [14]. A river diversion wetland can also be designed to operate with similar bed slope as

**6. Water conveying system: inlet and outlet structures of the wetland**

This aspect of the wetland design focused on selecting or designing a water conveying system, inlet and outlet control structures that can facilitate flow and distribute inflow and drain outflow water from the wetland effectively. Depending on the type of river diversion wetland, flow diversion structure may be designed to consist of either a pipe or channel system and should function to provide a controlled flow of water to the wetland. However, it is necessary to be explicit about flow capacity at the time of design so that appropriate sizing of flow diversion structure can be made. Generally, the design flow conveyance structure is based on hydraulic;

therefore the reader is referred to hydraulic books for detailed information.

should provide access for sampling and flow monitoring.

**66**

In order to ensure that the inflow water is uniformly distributed across the entire wetland area, multiple entry openings or gates should be considered rather than single to deliver the range of design flow regimes required. Flow control structures should be used to control inflow rate and maintain water levels. Control valves or weirs or a combination can be used depending on the type of inlet structured selected. Since the wetland system is for water quality improvement, high incoming water velocities should be discouraged. Therefore, energy dissipation system may be required for the incoming water to provide protection for the wetland inlet. The inlet openings should be designed large enough to avoid obstruction. Inlet zones

Wetland outlet design is essential in avoiding possible dead zones and controlling water level and for monitoring flow and water quality. Depending on the size of the wetland, a combination of outlets (primary and secondary) or multiple outlets consisting of hydraulic control structures can be considered to collect and discharge treated water for the range of design flow regimes and maintain required water storage level. The purpose of the primary outlets is for water quality control, while

out the wetland system and facilitate drainage. In order to minimize short-

recommended for FWS since they are related in mode of operation.

considerations.

*Inland Waters - Dynamics and Ecology*

coliform bacteria).

the most efficient aspect ratio.

The management and restoration of water bodies like rivers should go beyond protection through the use of regulations. It should also make the most of opportunities that arise from using ecosystem properties to enhance self-purification capacity of rivers for water quality improvement. A key consideration is the use of constructed river diversion wetlands.

This chapter provided guidance on the design of a river diversion constructed wetland aimed at improving quality of river water. The use of a combination of empirical equations was presented to guide in the estimation of the actual wetland area rather than relying on an assumed rate. The design approach using these equations may present a promising method for the design of river diversion wetlands. Furthermore, this novel approach may be useful to wetland experts as some of the procedures adopted are not popular in wetland studies. This may provide opportunity for wetland designers to document approaches that have been found promising and come up with suitable design criteria for constructed river diversion wetlands.

#### **Acknowledgements**

The authors wish to express appreciation for the funding support provided by the Regional Water and Environmental Sanitation Centre, Kumasi (RWESCK), at the Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, which is funded by the Government of Ghana and the World Bank under the Africa Centres of Excellence Project. Also, the authors wish to thank the National Water Resources Institute (NWRI), Nigeria, for providing opportunity and support for the study that led to the generation of knowledge and information presented in this chapter. We declare that the views expressed in this chapter are those of the authors and do not necessarily reflect those of the World Bank, Ghana Government, KNUST, and NWRI.

#### **Conflict of interest**

None declared.

*Inland Waters - Dynamics and Ecology*

### **Author details**

Sani Dauda Ahmed1,2\*, Sampson Kwaku Agodzo1 and Kwaku Amaning Adjei<sup>1</sup>

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*Designing River Diversion Constructed Wetland for Water Quality Improvement*

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1279-1286

**69**

1 Regional Water and Environmental Sanitation Centre Kumasi (RWESCK), Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

2 National Water Resources Institute, Kaduna, Nigeria

\*Address all correspondence to: sanidaud@yahoo.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Designing River Diversion Constructed Wetland for Water Quality Improvement DOI: http://dx.doi.org/10.5772/intechopen.92119*

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**Author details**

*Inland Waters - Dynamics and Ecology*

**68**

Sani Dauda Ahmed1,2\*, Sampson Kwaku Agodzo1 and Kwaku Amaning Adjei<sup>1</sup>

1 Regional Water and Environmental Sanitation Centre Kumasi (RWESCK), Kwame Nkrumah University of Science and Technology, Kumasi, Ghana

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

2 National Water Resources Institute, Kaduna, Nigeria

\*Address all correspondence to: sanidaud@yahoo.com

provided the original work is properly cited.

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[22] Kimwaga RJ, Mwegoha WJS, Mahenge A, Nyomora AM, Lugali LG. Factors for success and failures of constructed wetlands in sanitation service chain. In: Dissemination of the Sustainable Wastewater Technology of Constructed Wetlands in Tanzania (VLIR Research Project). 2013

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[24] Economopoulou MA, Tsihrintzis VA. Design methodology of free water surface constructed wetlands. Water Resources Management*.* 2004;**18**: 541-565

[32] Ajmal M, Khan TA, Kim T. A CNbased ensembled hydrological model for enhanced watershed runoff prediction. Water. 2016;**8**(20):1-17. DOI: 10.3390/

*DOI: http://dx.doi.org/10.5772/intechopen.92119*

*Designing River Diversion Constructed Wetland for Water Quality Improvement*

performance using the advection diffusion equation. WIT Transactions on Ecology and the Environment. 2008;

**109**(IV):363-371. DOI: 10.2495/

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[42] Crites RW, Tchobanoglous G. Small

Management Systems. New York, NY:

Middlebrooks EJ. Natural Systems for Waste Management and Treatment. 2nd ed. New York, USA: McGraw-Hill, Inc.;

[44] Kadlec RH, Knight RL. Treatment Wetlands. Boca Raton, USA: Lewis

[45] Kadlec RH. The inadequacy of firstorder treatment wetland models. Ecological Engineering. 2000;**15**:105-119

[46] Kayombo S, Mbwette TSA, Katima JHY, Ladegaard N, Jorgensen SE. Waste stabilization ponds and constructed wetlands design manual. Tanzania, Dar Es Salaam: UNEP-IETC with the Danish International Development Agency

[47] Kadlec RH, Reddy KR. Temperature effects in treatment wetlands. Water Environment Research. 2001;**73**(5):

[49] Mitchell C, McNevin D. Alternative analysis of BOD removal in subsurface flow constructed wetlands employing

[48] Kivaisi AK. The potential for constructed wetlands for wastewater treatment and reuse in developing countries: A review. Ecological Engineering. 2001;**16**:545-560

and Decentralized Wastewater

McGraw Hill Co.; 1998

[43] Reed SC, Crites RW,

1995

Publishers; 1996

(Danida); 2005

543-557

WM080381

[33] Duran-Barroso P, Gonzalez J, Valdes JB. Sources of uncertainty in the NRCS model: Recognition and solution. Hydrological Processes. 2017;**31**(22):1-9.

[34] Yuan Y, Nie W, McCutcheon SC, Taguas EV. Initial abstraction and curve numbers for semiarid watersheds in southeastern Arizona. Hydrological Processes. 2012;**28**(3):1-11. DOI:

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[36] Lenhart C, Gordon B, Gamble J, Current D, Ross N, Herring L, et al. Design and hydrologic performance of a tile drainage treatment wetland in Minnesota, USA. Water. 2016;**8**(549):

[37] Guven A, Aytek A, Azamathulla H. A practical approach to formulate stage– discharge relationship in natural rivers. Neural Computation and Application. 2012;**23**(3-4):873-880. DOI: 10.1007/

[38] Dottori F, Martina MLV, Todini E. A dynamic rating curve approach to indirect discharge measurement. Hydrology and Earth System Sciences

Discussions. 2009;**6**:859-896

[39] Biggs BJF. Hydraulic habitat of plants in streams. Regulated River Resource and Management. 1996;**12**:

[40] Popov V, Ahmed S, Qureshi MI. Simulation of constructed wetland

1-19. DOI: 10.3390/w8120549

s00521-012-1011-5

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[26] Ashbolt NJ, Grabow WOK, Snozzi M. 13: Indicators of microbial water quality. In: Fretwell L, Bartram J, editors. Water Quality: Guidelines, Standards and Health (World Health Organization (WHO)). London, UK: IWA Publishing; 2001

[27] Miller J. Constructed Wetlands Technology Assessment and Design Guidance (Manual). USA: Iowa Department of Natural Resources (IDNR); 2007

[28] Gikas GD, Tsihrintzis VA. Municipal wastewater treatment using constructed wetlands. Water Utility Journal. 2014;**8**:57-65

[29] HTCKL (Humid Tropics Hydrology and Water Resources Centre). Technical Report on Constructed Wetland. The Regional Humid Tropics Hydrology and Water Resources Centre for Southern Asia and the Pacific. Malaysia, Kuala Lumpur: HTCKL; 2014

[30] Millhollon EP, Rodrigue PB, Rabb JL, Martin DF, Anderson RA, Dans DR. Designing a constructed wetland for the detention of agricultural runoff for water quality improvement. Journal of Environmental Quality. 2009;**38**: 2458-2467. DOI: 10.2134/jeq2008.0526

[31] WSUD (Water Sensitive Urban Design). Constructed wetlands (Engineering Guidelines) for Brisbane City. Australia, Brisbane City; Brisbane City Councils; 2005

*Designing River Diversion Constructed Wetland for Water Quality Improvement DOI: http://dx.doi.org/10.5772/intechopen.92119*

[32] Ajmal M, Khan TA, Kim T. A CNbased ensembled hydrological model for enhanced watershed runoff prediction. Water. 2016;**8**(20):1-17. DOI: 10.3390/ w8010020

[17] Vymazal J. Emergent plants used in free water surface constructed wetlands: A review. Ecological Engineering. 2013; **61**(Part B):582-592. 1-11. DOI: 10.1016/j.

*Inland Waters - Dynamics and Ecology*

free water surface constructed wetlands. Water Resources Management*.* 2004;**18**:

[25] Chapman D, Kimstach V. Selection

of water quality variables. In: Chapman D, editor. Water Quality Assessments—A Guide to Use of Biota, Sediments and Water in Environmental Monitoring. 2nd ed. Cambridge, Great Britain: UNESCO/WHO/UNEP

[26] Ashbolt NJ, Grabow WOK, Snozzi M. 13: Indicators of microbial water quality. In: Fretwell L, Bartram J, editors. Water Quality: Guidelines, Standards and Health (World Health Organization (WHO)). London, UK:

[27] Miller J. Constructed Wetlands Technology Assessment and Design Guidance (Manual). USA: Iowa Department of Natural Resources

[28] Gikas GD, Tsihrintzis VA.

Municipal wastewater treatment using constructed wetlands. Water Utility

[29] HTCKL (Humid Tropics Hydrology and Water Resources Centre). Technical Report on Constructed Wetland. The Regional Humid Tropics Hydrology and Water Resources Centre for Southern Asia and the Pacific. Malaysia, Kuala

[30] Millhollon EP, Rodrigue PB, Rabb JL, Martin DF, Anderson RA, Dans DR. Designing a constructed wetland for the detention of agricultural runoff for water

quality improvement. Journal of Environmental Quality. 2009;**38**: 2458-2467. DOI: 10.2134/jeq2008.0526

[31] WSUD (Water Sensitive Urban Design). Constructed wetlands (Engineering Guidelines) for Brisbane City. Australia, Brisbane City; Brisbane

University Press; 1996

IWA Publishing; 2001

(IDNR); 2007

Journal. 2014;**8**:57-65

Lumpur: HTCKL; 2014

City Councils; 2005

541-565

[18] Westerhoff P, Sharif F, Halden R, Herckes P, Krajmalnik-Brown R. Constructed wetlands for treatment of organic and engineered nanomaterial contaminants of emerging concerns. In: Web Report No: 4334. Denver, USA: Water Research Foundation (WRF); 2014

[19] Mitsch WJ, Day W. Restoration of wetlands in the Mississippi–Ohio– Missouri (MOM) river basin: Experience and needed research. Ecological Engineering*.* 2006;**26**:55-69. DOI: 10.1016/j.ecoleng.2005.09.005

[20] Verhoeven JTA, Arheimer B, Yin C, Hefting MM. Regional and global concerns over wetlands and water quality. Trends in Ecology and Evolution. 2006;**21**(2):96-103

[21] Meybeck M, Kimstach V, Helmer R. Strategies for water quality assessment. In: Chapman D, editor. Water Quality Assessments—A Guide to Use of Biota, Sediments and Water in Environmental Monitoring. 2nd ed. Cambridge, Great Britain: UNESCO/WHO/UNEP

University Press; 1996

[22] Kimwaga RJ, Mwegoha WJS, Mahenge A, Nyomora AM, Lugali LG. Factors for success and failures of constructed wetlands in sanitation service chain. In: Dissemination of the Sustainable Wastewater Technology of Constructed Wetlands in Tanzania (VLIR Research Project). 2013

[23] USEPA. (U.S. Environmental Protection Agency) Constructed Wetlands for Treatment of Municipal Wastewater Manual (EPA 625/R-99/ 010). Cincinnati, OH: U.S. EPA; 2000

Tsihrintzis VA. Design methodology of

[24] Economopoulou MA,

**70**

ecoleng.2013.06.023

[33] Duran-Barroso P, Gonzalez J, Valdes JB. Sources of uncertainty in the NRCS model: Recognition and solution. Hydrological Processes. 2017;**31**(22):1-9. DOI: 10.1002/hyp.11305

[34] Yuan Y, Nie W, McCutcheon SC, Taguas EV. Initial abstraction and curve numbers for semiarid watersheds in southeastern Arizona. Hydrological Processes. 2012;**28**(3):1-11. DOI: 10.1002/hyp9592

[35] WMO (World Meteorological Organization). Manual on Stream Gauging: Volume II—Computation of Discharge (WMO-No. 1044). Geneva, Switzerland: World Meteorological Organization (WMO); 2010

[36] Lenhart C, Gordon B, Gamble J, Current D, Ross N, Herring L, et al. Design and hydrologic performance of a tile drainage treatment wetland in Minnesota, USA. Water. 2016;**8**(549): 1-19. DOI: 10.3390/w8120549

[37] Guven A, Aytek A, Azamathulla H. A practical approach to formulate stage– discharge relationship in natural rivers. Neural Computation and Application. 2012;**23**(3-4):873-880. DOI: 10.1007/ s00521-012-1011-5

[38] Dottori F, Martina MLV, Todini E. A dynamic rating curve approach to indirect discharge measurement. Hydrology and Earth System Sciences Discussions. 2009;**6**:859-896

[39] Biggs BJF. Hydraulic habitat of plants in streams. Regulated River Resource and Management. 1996;**12**: 131-144

[40] Popov V, Ahmed S, Qureshi MI. Simulation of constructed wetland

performance using the advection diffusion equation. WIT Transactions on Ecology and the Environment. 2008; **109**(IV):363-371. DOI: 10.2495/ WM080381

[41] Stairs DB. Flow characteristics of constructed wetlands: Tracer studies of the hydraulic regime [MSc thesis]. USA: Oregon State University; 1993. pp. 81

[42] Crites RW, Tchobanoglous G. Small and Decentralized Wastewater Management Systems. New York, NY: McGraw Hill Co.; 1998

[43] Reed SC, Crites RW, Middlebrooks EJ. Natural Systems for Waste Management and Treatment. 2nd ed. New York, USA: McGraw-Hill, Inc.; 1995

[44] Kadlec RH, Knight RL. Treatment Wetlands. Boca Raton, USA: Lewis Publishers; 1996

[45] Kadlec RH. The inadequacy of firstorder treatment wetland models. Ecological Engineering. 2000;**15**:105-119

[46] Kayombo S, Mbwette TSA, Katima JHY, Ladegaard N, Jorgensen SE. Waste stabilization ponds and constructed wetlands design manual. Tanzania, Dar Es Salaam: UNEP-IETC with the Danish International Development Agency (Danida); 2005

[47] Kadlec RH, Reddy KR. Temperature effects in treatment wetlands. Water Environment Research. 2001;**73**(5): 543-557

[48] Kivaisi AK. The potential for constructed wetlands for wastewater treatment and reuse in developing countries: A review. Ecological Engineering. 2001;**16**:545-560

[49] Mitchell C, McNevin D. Alternative analysis of BOD removal in subsurface flow constructed wetlands employing

Monod kinetics. Water Research. 2001; **35**(5):1295-1303

[50] Wynn TM, Liehr SK. Development of a constructed subsurface-flow wetland simulation model. Ecological Engineering. 2001;**16**:519-536

[51] Economopoulou MA, Tsihrintzis VA. Design methodology and area sensitivity analysis of horizontal subsurface flow constructed wetlands. Water Resources Management. 2003;**17**(2):147-174

[52] Sarah KL. Natural treatment and onsite processes. Water Environmental Research. 2005;**77**(6):1389-1424

[53] Moreno-Mateos D, Pedrocchi C, Comin FA. Effects of wetland construction on water quality in a semiarid catchment degraded by intensive agricultural use. Ecological Engineering*.* 2010;**36**:631-639

[54] Bendoricchio G, Cin LD, Persson J. Guidelines for free water surface wetland design. EcoSys Bd. 2000;**8**: 51-91

[55] Steiner GR, Freeman RJ. Configuration and substrate design considerations for constructed wetlands wastewater treatment. In: Hammer DA, editor. Constructed Wetlands for Wastewater Treatment. Chelsea, USA: Lewis Publishers; 1989

[56] Persson J, Somes NLG, Wong THF. Hydraulics efficiency of constructed wetlands and ponds. Water Science and Technology. 1999;**40**:291-300

**73**

**Figure 1.**

*Maumee Bay State Park, Ohio, 2013 HAB. Source: Ref. [2].*

**Chapter 5**

**Abstract**

**1. Introduction**

The Tourism Impacts of Lake Erie

Nutrient loading and warming waters can lead to hazardous algal blooms (HABs). Policymakers require cost-effective valuation tools to help understand impacts and prioritize adaptation measures. This chapter evaluates the tourism impacts of HABs in Western Lake Erie based on HABs that occurred in 2011 and 2014, both through a unique temporal and spatial specification of HAB severity as

well as input/output analysis and decomposition of trips and profitability.

**Keywords:** hazardous algal blooms, HABs, nutrient loading, socioeconomic,

Attractive inland waters such as western Lake Erie can provide significant tourism services [1]. Hazardous algal blooms (HABs) that tend to result from warm water and nutrient loading result in murky and unpleasant water (**Figure 1**), potentially interrupting the \$12.9 billion tourism industry in the region and putting

Hazardous Algal Blooms

*Matthew Bingham and Jason Kinnell*

benefits transfer, Lake Erie, input/output, tourism

#### **Chapter 5**

Monod kinetics. Water Research. 2001;

*Inland Waters - Dynamics and Ecology*

[50] Wynn TM, Liehr SK. Development of a constructed subsurface-flow wetland simulation model. Ecological

Tsihrintzis VA. Design methodology and area sensitivity analysis of

horizontal subsurface flow constructed

[52] Sarah KL. Natural treatment and onsite processes. Water Environmental Research. 2005;**77**(6):1389-1424

[53] Moreno-Mateos D, Pedrocchi C, Comin FA. Effects of wetland

construction on water quality in a semiarid catchment degraded by intensive agricultural use. Ecological Engineering*.*

[54] Bendoricchio G, Cin LD, Persson J. Guidelines for free water surface wetland design. EcoSys Bd. 2000;**8**:

[56] Persson J, Somes NLG, Wong THF. Hydraulics efficiency of constructed wetlands and ponds. Water Science and

[55] Steiner GR, Freeman RJ. Configuration and substrate design considerations for constructed wetlands wastewater treatment. In: Hammer DA, editor. Constructed Wetlands for Wastewater Treatment. Chelsea, USA:

Lewis Publishers; 1989

Technology. 1999;**40**:291-300

Engineering. 2001;**16**:519-536

[51] Economopoulou MA,

wetlands. Water Resources Management. 2003;**17**(2):147-174

2010;**36**:631-639

51-91

**72**

**35**(5):1295-1303
